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WM8351
Wolfson AudioPlus™ Stereo CODEC with Power Management
DESCRIPTION
FEATURES
The WM8351 is an integrated audio and power management
subsystem which provides a cost effective, single-chip solution
for portable audio and multimedia systems.
Stereo Hi-Fi CODEC
•
DAC SNR 95dB (‘A’ weighted @ 48kHz), THD –81dB
•
ADC SNR 95dB (‘A’ weighted @ 48kHz), THD –83dB
The integrated audio CODEC provides all the necessary
functions for high-quality stereo recording and playback.
Programmable on-chip amplifiers allow for the direct
connection of headphones and microphones with a minimum
of external components. A programmable low-noise bias
voltage is available to feed one or more electret microphones.
Additional audio features include programmable high-pass
filter in the ADC input path.
•
•
•
The WM8351 includes four programmable DC-DC converters,
four low-dropout (LDO) regulators and a current limit switch to
generate suitable supply voltages for each part of the system,
including the integrated audio CODEC as well as off-chip
components such as a digital core and I/O supplies, and LED
lighting. An additional on-chip regulator maintains the backup
power for always-on functions. The WM8351 can be powered
by a lithium battery, by a wall adaptor or USB.
An on-chip battery charger supports both trickle charging and
fast (constant current, constant voltage) charging of single-cell
lithium batteries. The charge current, termination voltage, and
charger time-out are programmable to suit different types of
batteries.
Internal power management circuitry controls the start-up and
shutdown sequencing of clocks and supply voltages. It also
detects and handles conditions such as under-voltage,
extreme temperatures, and deeply discharged or defective
batteries, with a minimum of software involvement.
A programmable constant-current sink is available for driving
LED strings, e.g. for display backlights or photo-flash
applications, in a highly power-efficient way. Additional RGB
LEDs can be driven through GPIO pins.
The WM8351 includes a 32.768kHz crystal oscillator, an
internal RC oscillator, a real-time clock (RTC) and an alarm
function capable of waking up the system. Internal circuitry
can generate all clock signals required to start up the device.
The master clock for the audio CODEC can be input directly,
or may be generated internally using an integrated, low power
Frequency Locked Loop (FLL).
To extend battery life, fine-grained power management
enables each function in the WM8351 to be independently
powered down through the control interface. The WM8351
forms part of the Wolfson AudioPlusTM series of audio and
power management solutions.
•
40mW on-chip headphone driver with ‘capless’ option
16Ω headphone load: THD -72dB, Po = 20mW
2 differential microphone inputs with low-noise bias
voltage and programmable preamps
Programmable high-pass filter for ADC
•
•
•
Microphone and Headphone detection
Auxiliary inputs for analogue signals
Sample rates: 8, 11.025, 16, 22.05, 24, 32, 44.1 or 48kHz
System Control
•
Support for 2-wire or 3-/4-wire Control Interface
•
Handles power sequencing, reset signals and fault
conditions
•
Autonomous power source selection (battery, wall adaptor
or USB bus)
•
Total current drawn from USB bus is limited to comply with
USB 2.0 standard and USB OTG supplement
Supply Generation
•
1 x DC-DC Buck Converter (0.85V - 3.4V, Up to 1A)
•
2 x DC-DC Buck Converters (0.85V - 3.4V, Up to 500mA)
•
1 x DC-DC Boost Converter (5V - 20V, 40 to 200mA)
•
4 x LDO voltage regulators (0.9V - 3.3V, 150mA)
LED Drivers
•
Programmable constant-current sink, suitable for screen
backlight or white LED photo flash
•
3 open-drain outputs for RGB LEDs
Battery Charger
•
Single-cell Li-Ion / Li-Pol battery charger
•
Thermal protection for charge control; temperature
monitoring available for thermal regulation
•
LED outputs to indicate charge status and fault conditions
Additional Features
•
•
•
“Always on” RTC with wake-up alarm
Watchdog timer
Up to 13 configurable GPIO pins
•
•
•
On-chip crystal oscillator and internal RC oscillator
Low power FLL supporting wide range of input clocks
7x7mm, 129 BGA package, 0.5mm ball pitch
APPLICATIONS
•
•
•
WOLFSON MICROELECTRONICS plc
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Portable Audio and Media players
Portable Navigation Devices
Portable systems powered by single-cell lithium batteries
Production Data, February 2011, Rev 4.4
Copyright ©2011 Wolfson Microelectronics plc
WM8351
Production Data
TYPICAL APPLICATIONS
The WM8351 is a complete audio and power management solution for portable media devices. The
device incorporates three programmable step-down switching regulators, a step-up switching
regulator, a full-featured battery charger, four Low Drop-Out (LDO) voltage regulators which can also
serve as hot-swap outputs, a backup supply regulator, a programmable white LED driver, a RealTime Clock (RTC) alongside a 32.768kHz (32kHz) oscillator capable of operating from a backup
battery, a 12-bit auxiliary ADC for precise measurements, a ROM-programmable power management
state machine and numerous protection features all in a single 7x7mm BGA package. When only
battery power is available, a battery switch provides power to all switching regulators (and some
other internal modules). When external power is applied (eg. from USB or Wall adapter), the
WM8351 seamlessly transitions from battery power (a single-cell Lithium battery) to the applicable
external supply. The battery charger is then activated, all internal power for the device is drawn from
the appropriate external power source and the battery is disconnected from the load. Maximum
battery charge current and charge time are programmable. The USB power manager provides
accurate current limiting for the USB pin under all conditions. The hot-swap outputs (LDOs in currentlimited ‘Switch Mode’ operation) are ideal for powering memory cards and other devices that can be
inserted while the system is fully powered.
The integrated Hi-Fi stereo CODEC incorporates preamps and a low-noise bias voltage for
differential microphones, and flexible pseudo-differential drivers for headphone and differential/singleended line outputs. External component requirements are reduced as no separate microphone or
headphone amplifiers are required. Digital filter options are available in the ADC and DAC paths, to
cater for application filtering. The WM8351 is capable of operating without any external clock, as it
can derive all required clocks from its internal crystal oscillator, RC clock, and Frequency Locked
Loop. An external low jitter clock may be required in some applications for high performance audio.
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LINEDCDC
PGND
PVDD
DGND
GND[0:10]
DBVDD
DCVDD
SDATA
SCLK
IRQ
*MASK/HEARTBEAT
MCLK
X2
X1
*32KHz
ROM
REGISTERS
CONTROL
INTERFACE
Interrupt
Logic
Watchdog
Timer
*GPIO Capability or
other Alternate Function
restart
FLL
OSC
32kHz
Differential
MICs
References
AUX ADC
AUX3
AUX4
days
hours
mins
secs
msecs
sync
RECORD
VOLUME
RECORD
SELECT
INPUT
PGAs
Control
interface
d_ready
ADC
Control
Logic
WALLFB
Real
Time
Clock
USB[0:2]
Power Supply Controller
ADC
R
ADC
L
Volume
Hi-Fi DAC
DIGITAL
FILTERS
I2S
INTERFACE
Programmable
Filters
Volume
Hi-Fi ADC
DIGITAL
FILTERS
DAC
R
DAC
L
WM8351
OUTPUT
MIXERS
DC-DC2
5V-20V
40mA
mclk
Interrupt
Logic
GPIO
DC-DC4
0.85V-3.4V
500mA
DC-DC3
0.85V-3.4V
500mA
VP2
FB2
NGATE2
L2
PG2
VRTC
HIVDD
DC-DC1
0.85V-3.4V
1A
Memory
Supply
PV3
L3
FB3
PG3
Wake-Up
Timer
LINE[0:2]
Power
Switches
BATT[0:2]
Power
Management
Battery
Charge
Controller
PG1[0:1]
FB1
L1[0:1]
PV1[0:1]
2MHZ
RC OSC
Sub System
Core Supply
PV4
L4
FB4
PG4
USB OTG
Supply
OUT2R_VOL
OUT2L_VOL
OUT1R_VOL
OUT1L_VOL
LDO 3
150mA
LDO 4
150mA
LDO 1
150mA
LDO 2
150mA
Limit
Switch
LED
Drivers
LINEINT
SWVRTC
*LINE_SW
*FLASH/ MR
*LDO_ENA
*PWR_ON
/RST
ON
Digital Core
Supply
HPCOM
OUT2R
OUT2L
OUT1R
OUT1L
OUT4
OUT3
LDOVDD
VOUT4
VINB
VOUT3
VOUT2
VINA
VOUT1
IP
OP
*ISINKE
*ISINKD/ WAKEUP
*ISINKC/CH_IND
ISINKA
Production Data
WM8351
BLOCK DIAGRAM
AUX1
AUX2
HPGND
HPVDD
*PWR_OFF/P_CLK
*L_PWR1
*L_PWR2
*L_PWR3
ADCDATA
DACDATA
LRCLK
BCLK
VMID
AVDD
REFGND
CONF0
CONF1
IN3R
IN3L
IN1RN
IN2R
IN1RP
IN1LN
IN2L
IN1LP
MICBIAS
CREF
RREF
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WM8351
Production Data
TABLE OF CONTENTS
DESCRIPTION ....................................................................................................... 1
FEATURES............................................................................................................. 1
APPLICATIONS ..................................................................................................... 1
TYPICAL APPLICATIONS ..................................................................................... 2
BLOCK DIAGRAM ................................................................................................. 3
TABLE OF CONTENTS ......................................................................................... 4
1
PIN CONFIGURATION .................................................................................. 9
2
ORDERING INFORMATION .......................................................................... 9
3
PIN DESCRIPTION ...................................................................................... 10
4
THERMAL CHARACTERISTICS ................................................................. 13
5
ABSOLUTE MAXIMUM RATINGS .............................................................. 14
6
RECOMMENDED OPERATING CONDITIONS ........................................... 15
7
ELECTRICAL CHARACTERISTICS ............................................................ 16
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
8
9
HI-FI AUDIO CODEC ......................................................................................... 16
DC-DC STEP UP CONVERTER ELECTRICAL CHARACTERISTICS ............... 18
DC-DC STEP DOWN CONVERTER ELECTRICAL CHARACTERISTICS ........ 19
LDO REGULATOR ELECTRICAL CHARACTERISTICS ................................... 21
BATTERY CHARGER........................................................................................ 22
CURRENT LIMIT SWITCH ................................................................................ 22
LED DRIVERS ................................................................................................... 23
GENERAL PURPOSE INPUTS / OUTPUTS (GPIO) ......................................... 23
DIGITAL INTERFACES ..................................................................................... 24
AUXILIARY ADC ............................................................................................ 24
TYPICAL POWER CONSUMPTION ............................................................ 25
TYPICAL PERFORMANCE DATA............................................................... 27
9.1
9.2
AUDIO CODEC.................................................................................................. 27
DC-DC CONVERTERS...................................................................................... 28
9.2.1
9.2.2
9.2.3
9.3
10
LDO REGULATORS .......................................................................................... 31
SIGNAL TIMING REQUIREMENTS............................................................. 32
10.1
10.2
10.3
10.4
10.5
11
POWER EFFICIENCY ............................................................................................................. 28
OUTPUT VOLTAGE REGULATION ........................................................................................ 29
DYNAMIC OUTPUT VOLTAGE ............................................................................................... 30
SYSTEM CLOCK TIMING .............................................................................. 32
AUDIO INTERFACE TIMING - MASTER MODE ............................................ 32
AUDIO INTERFACE TIMING - SLAVE MODE................................................ 33
AUDIO INTERFACE TIMING - TDM MODE ................................................... 34
CONTROL INTERFACE TIMING.................................................................... 35
CONTROL INTERFACE .............................................................................. 38
11.1
11.2
11.3
11.4
11.5
11.6
11.7
GENERAL DESCRIPTION ............................................................................. 38
CONTROL INTERFACE MODES ................................................................... 38
2-WIRE SERIAL CONTROL MODE ............................................................... 39
3-WIRE SERIAL CONTROL MODE ............................................................... 42
4-WIRE SERIAL CONTROL MODE ............................................................... 43
REGISTER LOCKING .................................................................................... 44
SPECIAL REGISTERS ................................................................................... 44
11.7.1
11.7.2
12
CHIP ID ................................................................................................................................ 44
DEVICE INFORMATION ...................................................................................................... 44
CLOCKING, TIMING AND SAMPLE RATES .............................................. 45
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12.1
GENERAL DESCRIPTION ............................................................................. 45
12.1.1
12.1.2
12.1.3
12.2
12.3
CRYSTAL OSCILLATOR................................................................................ 46
CLOCKING AND SAMPLE RATES ................................................................ 47
12.3.1
12.3.2
12.3.3
12.3.4
12.3.5
12.3.6
12.4
SYSCLK CONTROL............................................................................................................. 49
ADC / DAC SAMPLE RATES............................................................................................... 50
BCLK CONTROL ................................................................................................................. 52
ADCLRCLK / DACLRCLK CONTROL ................................................................................. 54
OPCLK CONTROL .............................................................................................................. 55
SLOWCLK CONTROL ......................................................................................................... 55
FLL ................................................................................................................. 55
12.4.1
12.4.2
13
CLOCKING THE AUDIO CODEC ........................................................................................ 46
CLOCKING THE DC-DC CONVERTERS ............................................................................ 46
INTERNAL RC OSCILLATOR .............................................................................................. 46
EXAMPLE FLL CALCULATION ........................................................................................... 58
EXAMPLE FLL SETTINGS .................................................................................................. 59
AUDIO CODEC SUBSYSTEM ..................................................................... 60
13.1
13.2
13.3
13.4
GENERAL DESCRIPTION ............................................................................. 60
AUDIO PATHS ............................................................................................... 61
ENABLING THE AUDIO CODEC ................................................................... 62
INPUT SIGNAL PATH .................................................................................... 64
13.4.1
13.4.2
13.4.3
13.4.4
13.4.5
13.4.6
13.4.7
13.5
ANALOGUE TO DIGITAL CONVERTER (ADC) ............................................. 71
13.5.1
13.5.2
13.6
OUT1L AND OUT1R ............................................................................................................ 82
OUT2L AND OUT2R ............................................................................................................ 84
HEADPHONE OUTPUTS EXTERNAL CONNECTIONS ..................................................... 86
OUT3 AND OUT4 ................................................................................................................ 88
DIGITAL AUDIO INTERFACE ........................................................................ 90
13.10.1
13.10.2
13.10.3
13.10.4
13.11
13.12
ENABLING THE ANALOGUE OUTPUTS ............................................................................ 78
OUTPUT MIXERS ................................................................................................................ 79
ANALOGUE OUTPUTS .................................................................................. 82
13.9.1
13.9.2
13.9.3
13.9.4
13.10
DAC PLAYBACK VOLUME CONTROL ............................................................................... 75
DAC SOFT MUTE AND SOFT UN-MUTE............................................................................ 75
DAC DE-EMPHASIS ............................................................................................................ 76
DAC OUTPUT PHASE AND MONO MIXING ....................................................................... 77
DAC STOPBAND ATTENUATION ....................................................................................... 77
OUTPUT SIGNAL PATH ................................................................................ 78
13.8.1
13.8.2
13.9
DIGITAL SIDETONE ............................................................................................................ 73
DIGITAL TO ANALOGUE CONVERTER (DAC) ............................................. 74
13.7.1
13.7.2
13.7.3
13.7.4
13.7.5
13.8
ADC VOLUME CONTROL ................................................................................................... 72
ADC HIGH-PASS FILTER.................................................................................................... 72
DIGITAL MIXING ............................................................................................ 73
13.6.1
13.7
MICROPHONE INPUTS ...................................................................................................... 64
ENABLING THE PRE-AMPLIFIERS .................................................................................... 65
SELECTING INPUT SIGNALS ............................................................................................. 65
CONTROLLING THE PRE-AMPLIFIER GAINS ................................................................... 66
MICROPHONE BIASING ..................................................................................................... 67
AUXILIARY INPUTS (IN3L AND IN3R) ................................................................................ 68
INPUT MIXERS .................................................................................................................... 69
AUDIO DATA FORMATS ..................................................................................................... 90
AUDIO INTERFACE TDM MODE ........................................................................................ 93
TDM DATA FORMATS......................................................................................................... 93
LOOPBACK ......................................................................................................................... 96
COMPANDING ............................................................................................... 96
ADDITIONAL CODEC FUNCTIONS ............................................................... 98
13.12.1
HEADPHONE JACK DETECT ............................................................................................. 98
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13.12.2
13.12.3
13.12.4
13.12.5
13.12.6
13.12.7
14
POWER MANAGEMENT SUBSYSTEM .................................................... 105
14.1
14.2
GENERAL DESCRIPTION ........................................................................... 105
POWER MANAGEMENT OPERATING STATES ......................................... 105
14.2.1
14.3
14.4
OVERVIEW........................................................................................................................ 139
DC-DC STEP DOWN CONVERTERS ............................................................................... 140
DC-DC STEP UP CONVERTER ........................................................................................ 141
LDO REGULATOR OPERATION ................................................................. 142
CURRENT LIMIT SWITCH ........................................................................ 143
15.1
15.2
GENERAL DESCRIPTION ........................................................................... 143
CONFIGURING THE CURRENT LIMIT SWITCH......................................... 143
15.2.1
15.2.2
15.2.3
16
LDO REGULATOR ENABLE ............................................................................................. 134
LDO REGULATOR CONTROL .......................................................................................... 135
INTERRUPTS AND FAULT PROTECTION ....................................................................... 137
ADDITIONAL CONTROL FOR LDO1 ................................................................................ 138
DC-DC CONVERTER OPERATION ............................................................. 139
14.8.1
14.8.2
14.8.3
14.9
DC-DC CONVERTER ENABLE ......................................................................................... 126
CLOCKING ........................................................................................................................ 126
DC-DC BUCK (STEP-DOWN) CONVERTER CONTROL.................................................. 127
DC-DC BOOST (STEP-UP) CONVERTER CONTROL...................................................... 130
INTERRUPTS AND FAULT PROTECTION ....................................................................... 132
CONFIGURING THE LDO REGULATORS .................................................. 134
14.7.1
14.7.2
14.7.3
14.7.4
14.8
CONFIGURATION MODE 01 ............................................................................................ 117
CONFIGURATION MODE 10 ............................................................................................ 120
CONFIGURATION MODE 11 ............................................................................................ 123
CONFIGURING THE DC-DC CONVERTERS .............................................. 126
14.6.1
14.6.2
14.6.3
14.6.4
14.6.5
14.7
CONTROL INTERFACE REDIRECTION ........................................................................... 111
STARTING UP IN DEVELOPMENT MODE ....................................................................... 112
CONFIGURING THE WM8351 IN DEVELOPMENT MODE .............................................. 113
CUSTOM MODES ........................................................................................ 116
14.5.1
14.5.2
14.5.3
14.6
STARTUP .......................................................................................................................... 107
POWER-UP SEQUENCING .............................................................................................. 108
SHUTDOWN ...................................................................................................................... 108
POWER CYCLING ............................................................................................................ 109
REGISTER RESET ............................................................................................................ 109
RESET SIGNALS............................................................................................................... 110
DEVELOPMENT MODE ............................................................................... 111
14.4.1
14.4.2
14.4.3
14.5
HIBERNATE STATE SELECTION ..................................................................................... 106
POWER SEQUENCING AND CONTROL .................................................... 107
14.3.1
14.3.2
14.3.3
14.3.4
14.3.5
14.3.6
15
MICROPHONE DETECTION ............................................................................................... 99
MID-RAIL REFERENCE (VMID) ........................................................................................ 100
ANTI-POP CONTROL ........................................................................................................ 101
UNUSED ANALOGUE INPUTS/OUTPUTS ....................................................................... 102
ZERO CROSS TIMEOUT .................................................................................................. 104
INTERRUPTS AND FAULT PROTECTION ....................................................................... 104
CURRENT LIMIT SWITCH ENABLE ................................................................................. 143
CURRENT LIMIT SWITCH BULK DETECTION CONTROL .............................................. 144
INTERRUPTS AND FAULT PROTECTION ....................................................................... 144
CURRENT SINKS (LED DRIVERS) .......................................................... 146
16.1
16.2
GENERAL DESCRIPTION ........................................................................... 146
CONSTANT-CURRENT SINK ...................................................................... 146
16.2.1
16.2.2
16.2.3
16.2.4
16.2.5
ENABLING THE SINK CURRENT ..................................................................................... 146
PROGRAMMING THE SINK CURRENT............................................................................ 146
FLASH MODE .................................................................................................................... 147
ON/OFF RAMP TIMING ..................................................................................................... 149
INTERRUPTS AND FAULT PROTECTION ....................................................................... 149
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16.3
16.4
17
OPEN-DRAIN LED OUTPUTS ..................................................................... 150
LED DRIVER CONNECTIONS ..................................................................... 150
POWER SUPPLY CONTROL .................................................................... 151
17.1
17.2
17.3
17.4
17.5
17.6
17.7
GENERAL DESCRIPTION ........................................................................... 151
BATTERY POWERED OPERATION ............................................................ 152
WALL ADAPTOR (LINE) POWERED OPERATION ..................................... 152
USB POWERED OPERATION ..................................................................... 153
EXTERNAL INTERRUPTS ........................................................................... 155
BACKUP POWER ........................................................................................ 155
BATTERY CHARGER .................................................................................. 156
17.7.1
17.7.2
17.7.3
17.7.4
17.7.5
17.7.6
17.7.7
17.7.8
18
19
SYSTEM MONITORING AND UNDERVOLTAGE LOCKOUT (UVLO) ..... 167
AUXILIARY ADC ........................................................................................ 169
19.1
19.2
19.3
19.4
19.5
19.6
19.7
20
GENERAL DESCRIPTION ........................................................................... 169
INITIATING AUXADC MEASUREMENTS .................................................... 170
VOLTAGE SCALING AND REFERENCES................................................... 172
AUXADC READBACK .................................................................................. 173
CALIBRATION .............................................................................................. 175
DIGITAL COMPARATORS ........................................................................... 176
AUXADC INTERRUPTS ............................................................................... 177
GENERAL PURPOSE INPUTS / OUTPUTS (GPIO) ................................. 178
20.1
GENERAL DESCRIPTION ........................................................................... 178
20.1.1
20.1.2
20.1.3
20.2
MAIN REFERENCE (VREF) ......................................................................... 188
LOW-POWER REFERENCE........................................................................ 188
REAL-TIME CLOCK (RTC)........................................................................ 189
22.1
22.2
GENERAL DESCRIPTION ........................................................................... 189
RTC CONTROL ............................................................................................ 189
22.2.1
22.2.2
22.2.3
22.2.4
22.2.5
22.3
22.4
22.5
23
24
LIST OF ALTERNATE FUNCTIONS .................................................................................. 181
SELECTING GPIO ALTERNATE FUNCTIONS ................................................................. 184
VOLTAGE REFERENCES ......................................................................... 188
21.1
21.2
22
CONFIGURING GPIO PINS .............................................................................................. 179
INPUT DE-BOUNCE .......................................................................................................... 180
GPIO INTERRUPTS .......................................................................................................... 180
GPIO ALTERNATE FUNCTIONS ................................................................. 181
20.2.1
20.2.2
21
GENERAL DESCRIPTION................................................................................................. 156
BATTERY CHARGER ENABLE ......................................................................................... 158
TRICKLE CHARGING ........................................................................................................ 158
FAST CHARGING .............................................................................................................. 160
BATTERY CHARGER TIMEOUT AND TERMINATION ..................................................... 162
BATTERY CHARGER STATUS ......................................................................................... 163
BATTERY FAULT CONDITIONS ....................................................................................... 164
INTERRUPTS AND FAULT PROTECTION ....................................................................... 166
MODES OF OPERATION .................................................................................................. 189
RTC TIME REGISTERS ..................................................................................................... 189
SETTING THE TIME .......................................................................................................... 190
RTC ALARM REGISTERS ................................................................................................. 190
SETTING THE ALARM ...................................................................................................... 192
TRIMMING THE RTC ................................................................................... 192
RTC GPIO OUTPUT..................................................................................... 193
RTC INTERRUPTS ...................................................................................... 195
WATCHDOG TIMER .................................................................................. 196
INTERRUPT CONTROLLER ..................................................................... 198
24.1
CONFIGURING THE IRQ PIN ...................................................................... 199
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24.2
24.3
Production Data
FIRST LEVEL INTERRUPTS ....................................................................... 199
SECOND-LEVEL INTERRUPTS .................................................................. 200
24.3.1
24.3.2
24.3.3
24.3.4
24.3.5
24.3.6
24.3.7
24.3.8
24.3.9
24.3.10
24.3.11
24.3.12
25
TEMPERATURE SENSING ....................................................................... 208
25.1
26
OVERVIEW .................................................................................................. 209
REGISTER BITS BY ADDRESS................................................................ 218
DIGITAL FILTER CHARACTERISTICS ..................................................... 316
28.1
28.2
29
CHIP TEMPERATURE MONITORING ......................................................... 208
REGISTER MAP ........................................................................................ 209
26.1
27
28
DAC FILTER RESPONSES .......................................................................... 316
ADC FILTER RESPONSES .......................................................................... 317
APPLICATIONS INFORMATION ............................................................... 318
29.1
29.2
29.3
29.4
TYPICAL CONNECTIONS ........................................................................... 318
VOLTAGE REFERENCE (VREF) COMPONENTS ....................................... 319
DC-DC (STEP-DOWN) CONVERTER EXTERNAL COMPONENTS ............ 319
DC-DC (STEP-UP) CONVERTER EXTERNAL COMPONENTS .................. 321
29.4.1
29.4.2
29.4.3
29.4.4
29.5
29.6
30
31
32
OVERCURRENT INTERRUPTS ........................................................................................ 200
UNDERVOLTAGE INTERRUPTS ...................................................................................... 200
CURRENT SINK (LED DRIVER) INTERRUPTS ................................................................ 201
EXTERNAL INTERRUPTS ................................................................................................ 201
CODEC INTERRUPTS ...................................................................................................... 201
GPIO INTERRUPTS .......................................................................................................... 203
AUXADC AND DIGITAL COMPARATOR INTERRUPTS................................................... 204
RTC INTERRUPTS ............................................................................................................ 204
SYSTEM INTERRUPTS ..................................................................................................... 205
CHARGER INTERRUPTS ................................................................................................. 205
USB INTERRUPTS ............................................................................................................ 206
WAKE-UP INTERRUPTS .................................................................................................. 207
DC-DC (STEP-UP) CONVERTER - CONSTANT VOLTAGE MODE ................................. 321
DC-DC (STEP-UP) CONVERTER - CONSTANT CURRENT MODE ................................. 323
DC-DC (STEP-UP) CONVERTER - USB MODE ............................................................... 324
DC-DC (STEP-UP) CONVERTER RECOMMENDED COMPONENTS ............................. 324
LDO REGULATOR EXTERNAL COMPONENTS ......................................... 325
PCB LAYOUT ............................................................................................... 326
PACKAGE DIAGRAM ................................................................................ 327
IMPORTANT NOTICE ................................................................................ 328
REVISION HISTORY ................................................................................. 329
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1
PIN CONFIGURATION
1
2
3
4
5
6
7
8
9
10
11
12
13
A
DNC
DNC
OP
PV1
L1
PG1
DNC
DNC
DNC
D NC
GPIO12
FB2
PG2
B
DNC
DNC
IP
PV1
L1
PG1
DNC
DNC
DNC
PVDD
GPIO10
NGATE2
VP2
C
L4
PG4
FB4
DNC
LINEDCD
C
FB1
GND
GND
AUX4
GPIO11
PGND
PG3
L2
D
PV4
BATT
HIVDD
N/A
N/A
N/A
N/A
N/A
N/A
N/A
FB3
PV3
L3
E
BATT
BATT
WALLFB
N/A
N/A
N/A
N/A
N/A
N/A
N/A
ISINKA
DNC
SINKGND
F
LINE
LINE
LIN E
N/A
N/A
GND
GND
GND
N/A
N/A
VOUT4
LDO VDD
VINB
G
USB
USB
U SB
N/A
N/A
GND
GND
GND
N/A
N/A
VOUT2
VOUT3
VINA
H
VRTC
LINEINT
CREF
N/A
N/A
GND
GND
GND
N/A
N/A
AUX1
VOUT1
AUX3
J
CONF0
X1
RREF
N/A
N/A
N/A
N/A
N/A
N/A
N/A
OUT1R
HPCOM
AUX2
K
CONF1
ON
X2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
OUT1L
OUT4
HPVDD
L
G PIO0
/RST
SW VRTC
IR Q
GPIO5
GPIO 8
GPIO9
BCLK
LRCLK
IN3L
IN 1LN
OUT3
HPGND
M
G PIO2
GPIO1
SDA
GPIO6
DGND
MCLK
ADCDATA
AVD D
IN3R
INL2
MICBIAS
OUT2R
OUT2L
N
G PIO3
SCL
GPIO4
GPIO7
DCVDD
DBVDD
VMID
IN1LP
INR2
IN1RP
IN1RN
DACDATA REFG ND
7mm x 7mm BGA1Z
Notes:
Pin names beginning with a lower-case "n" indicate that the pin is active low.
Colour coding indicates function of pins in typical usage:
DC-DC converters
LDO voltage regulators
Power m anagem ent functions
Analogue pins for audio codec
Digital pins for audio codec
Quiet ground
Others
2
ORDERING INFORMATION
ORDER CODE
TEMPERATURE
RANGE
PACKAGE
MOISTURE SENSITIVITY
LEVEL
PEAK SOLDERING
TEMPERATURE
WM8351GEB/V
-25°C to +85°C
129-ball BGA (7 x 7 mm)
(Pb-free)
MSL3
260oC
WM8351GEB/RV
-25°C to +85°C
129-ball BGA (7 x 7 mm)
(Pb-free, tape and reel)
MSL3
260oC
Note:
Reel quantity = 2,200
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PIN DESCRIPTION
Notes:
Pins are listed in alphabetical order by name.
NAME
LOCATION(S)
TYPE
ADCDATA
M7
Digital Output
AUX1
H11
POWER
DOMAIN
DESCRIPTION
DBVDD
Digital audio output (typically from on-chip audio ADC to
external IC)
Analogue Input
LINE
Auxiliary ADC input AUX1
(Special function for connection to temperature-sensing
NTC resistor in battery pack)
AUX2
J13
Analogue Input
LINE
Auxiliary ADC input AUX2
AUX3
H13
Analogue Input
LINE
Auxiliary ADC input AUX3
LINE
Auxiliary ADC input AUX4
AUX4
C9
Analogue Input
AVDD
M8
Supply
BATT
E1, E2, D2
Analogue I/O
Analogue supply for audio CODEC
Main battery power connection (can draw power or
charge battery)
BCLK
L8
Digital I/O
DBVDD
Bit clock signal for digital audio interface
CREF
H3
Analogue Output
VRTC
Decoupling for VREF reference voltage (connect
capacitor here)
CONF0
J1
Digital Input
VRTC
Start-up configuration pin 0
CONF1
K1
Digital Input
VRTC
Start-up configuration pin 1
DACDATA
N7
Digital Input
DBVDD
Digital audio input (typically from external IC to on-chip
audio DAC)
DCVDD
N5
Supply
Digital core supply; powers digital core of audio CODEC
DBVDD
N6
Supply
Digital I/O buffer supply; powers digital audio interface,
control interface and pins GPIO4 to GPIO9
DGND
M5
Supply
Digital ground; return path for DCVDD and DBVDD
supplies
FB1
C6
Analogue Input
PV1
DC-DC1 feedback pin
FB2
A12
Analogue Input
VP2
DC-DC2 feedback pin
FB3
D11
Analogue Input
PV3
DC-DC3 feedback pin
FB4
C3
Analogue Input
PV4
DC-DC4 feedback pin
GND
F6, F7, F8, G6,
G7, G8, H6, H7
H8, C7, C8
Supply
Quiet ground connection for audio CODEC.
Note that DC-DC Converters use a separate ground
connection.
GPIO0
L1
Digital I/O
VRTC
GPIO1
M2
Digital I/O
VRTC
General Purpose Input/Output pin 0
General Purpose Input/Output pin 1
GPIO2
M1
Digital I/O
VRTC
General Purpose Input/Output pin 2
GPIO3
N1
Digital I/O
VRTC
General Purpose Input/Output pin 3
GPIO4
N3
Digital I/O
DBVDD
General Purpose Input/Output pin 4
GPIO5
L5
Digital I/O
DBVDD
General Purpose Input/Output pin 5
GPIO6
M4
Digital I/O
DBVDD
General Purpose Input/Output pin 6
GPIO7
N4
Digital I/O
DBVDD
General Purpose Input/Output pin 7
GPIO8
L6
Digital I/O
DBVDD
General Purpose Input/Output pin 8
GPIO9
L7
Digital I/O
DBVDD
General Purpose Input/Output pin 9
GPIO10
B11
Digital I/O
LINE
General Purpose Input/Output pin 10
GPIO11
C10
Digital I/O
LINE
General Purpose Input/Output pin 11
GPIO12
A11
Digital I/O
LINE
HIVDD
D3
Analogue Output
HPCOM
J12
Analogue Input
HPGND
L13
Supply
HPVDD
K13
Supply
IN1LN
L11
Analogue Input
w
General Purpose Input/ Output pin 12
Analogue output from power management unit which
determines highest supply from Line, Battery or USB.
HPVDD
Headphone output amplifier noise compensation input
HPVDD
Headphone ground; return path for HPVDD supply
Headphone supply – powers the analogue outputs
OUT1L, OUT1R, OUT2L, OUT2R, OUT3 and OUT4
AVDD
Inverting input for left microphone channel
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Production Data
NAME
LOCATION(S)
TYPE
POWER
DOMAIN
DESCRIPTION
IN1LP
N10
Analogue Input
AVDD
IN1RN
N13
Analogue Input
AVDD
Non-inverting input 1 for left microphone channel
Inverting input for right microphone channel
IN1RP
N12
Analogue Input
AVDD
Non-inverting input 1 for right microphone channel
Non-inverting input 2 for left microphone channel
IN2L
M10
Analogue Input
AVDD
IN2R
N11
Analogue Input
AVDD
Non-inverting input 2 for right microphone channel
IN3L
L10
Analogue Input
AVDD
Auxiliary input for analogue audio signals (left channel)
IN3R
M9
Analogue Input
AVDD
Auxiliary input for analogue audio signals (right channel)
IP
B3
Analogue Input
ISINKA
E11
Analogue Output
LDOVDD
Constant-current LED driver A
L1
A5, B5
Analogue I/O
PV1
DC-DC1 inductor connection
L2
C13
Analogue I/O
VP2
DC-DC2 inductor connection
L3
D13
Analogue I/O
PV3
DC-DC3 inductor connection
L4
C1
Analogue I/O
PV4
DC-DC4 inductor connection
LDOVDD
F12
Supply
LDO amplifier supply voltage
LINEDCDC
C5
Supply
Supply connection for DC-DC 1 and 4 control circuits
LINEINT
H2
Supply
Supply connection for Internal Reference circuits
LINE
F1, F2, F3
Supply
LINE supply connection
LRCLK
L9
Digital I/O
DBVDD
Word clock (left/right clock) signal for digital audio
interface
Power input to current limit switch
MCLK
M6
Digital I/O
DBVDD
Master Clock (may be generated internally or externally)
MICBIAS
M11
Analogue Output
AVDD
Low-noise bias voltage for condenser microphones
(connect decoupling capacitor here)
NGATE2
B12
Analogue Output
VP2
DC-DC2 connection to gate of external power FET
IRQ
L4
Digital Output
open-drain
DBVDD
Interrupt signal from WM8351 to host processor
ON
K2
Digital Input
/RST
L2
Digital Output
open-drain
OP
A3
Analogue Output
OUT1L
K11
Analogue Output
VRTC
Connection for power-on switch
DBVDD
System Reset Signal (active low)
AVDD
Left channel analogue audio output 1
Power output from current limit switch
OUT2L
M13
Analogue Output
AVDD
Left channel analogue audio output 2
OUT1R
J11
Analogue Output
AVDD
Right channel analogue audio output 1
OUT2R
M12
Analogue Output
AVDD
Right channel analogue audio output 2
OUT3
L12
Analogue Output
AVDD
Analogue audio output 3 (or pseudo-ground output for
capacitor-less headphone outputs)
OUT4
K12
Analogue Output
AVDD
Analogue audio output 4
PG1
A6, B6
Supply
DC-DC1 power ground
PG2
A13
Supply
DC-DC2 power ground
PG3
C12
Supply
DC-DC3 power ground
PG4
C2
Supply
DC-DC4 power ground
PGND
C11
Supply
Ground connection
PV1
A4, B4,
Supply
DC-DC1 line or battery power input
PV3
D12
Supply
DC-DC3 line or battery power input
PV4
D1
Supply
DC-DC4 line or battery power input
PVDD
B10
Supply
Supply connection for DC-DC 2 and 3 control circuits
REFGND
N8
Supply
Reference ground for audio ADC and DAC
RREF
J3
Analogue Output
SCLK
N2
Digital Input
DBVDD
Clock signal for 2-wire serial control interface (5V
Tolerant)
DBVDD
Data line for 2-wire serial control interface (5V Tolerant)
VRTC
Switchable VRTC output. Typically used for battery
temperature monitoring
SDATA
M3
Digital I/O
SINKGND
E13
Supply
SWVRTC
L3
Analogue Output
w
Connection for external 100kΩ current reference resistor
Ground connection for ISINKA
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Production Data
NAME
LOCATION(S)
TYPE
POWER
DOMAIN
DESCRIPTION
USB
G1, G2, G3
Supply
Connection to USB power rail
VINA
G13
Supply
Input to voltage regulators LDO1 and LDO2
VINB
F13
Supply
VMID
N9
Analogue I/O
AVDD
Reference voltage (normally AVDD/2) for audio CODEC
(connect capacitor here)
VOUT1
H12
Analogue Output
VINA
Output of voltage regulator LDO1
VOUT2
G11
Analogue Output
VINA
Output of voltage regulator LDO2
VOUT3
G12
Analogue Output
VINB
Output of voltage regulator LDO3
VOUT4
F11
Analogue Output
VINB
Output of voltage regulator LDO4
Input to voltage regulators LDO3 and LDO4
VP2
B13
Supply
DC-DC2 power input
VRTC
H1
Supply
Backup power connection (WM8351 can draw power
from this pin or re-charge the backup power source)
WALLFB
E3
Analogue Input
LINE
Connection to Wall feedback
X1
J2
Analogue Input
VRTC
Connection for 32.768kHz crystal (input to oscillator from
crystal) or 32.768kHz external clock input (when not
using crystal)
X2
K3
Analogue Output
VRTC
Connection for 32.768kHz crystal (output from oscillator
to crystal)
DNC
A1, A2, A7, A8,
A9, A10, B1, B2,
B7, B8, B9, C4,
E12
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4
THERMAL CHARACTERISTICS
Thermal analysis must be performed in the intended application to prevent the WM8351 from
exceeding maximum junction temperature. Several contributing factors affect thermal performance
most notably the physical properties of the mechanical enclosure, location of the device on the PCB
in relation to surrounding components and the number of PCB layers. Connecting the nine central
GND balls through thermal vias and into a large ground plane will aid heat extraction.
Three main heat transfer paths exist to surrounding air:
-
Package top to air (radiation).
-
Package bottom to PCB (radiation).
-
Package leads to PCB (conduction).
The temperature rise TR is given by TR = PD * ӨJA
-
PD is the power dissipated by the device.
-
ӨJA is the thermal resistance from the junction of the die to the ambient temperature
and is therefore a measure of heat transfer from the die to surrounding air.
-
For WM8351, ӨJA = 32°C/W
The junction temperature TJ is given by TJ = TA + TR
1.
TA, is the ambient temperature.
The worst case conditions are when the WM8351 is operating in a high ambient temperature, with
low supply voltage, high duty cycle and high output current. Under such conditions, it is possible that
the heat dissipated could exceed the maximum junction temperature of the device. Care must be
taken to avoid this situation. An example calculation of the junction temperature is given below.
-
PD = 1W (example figure)
-
ӨJA = 32°C/W
-
TR = PD * ӨJA = 32°C
-
TA = 85°C (example figure)
-
TJ = TA +TR = 117°C
The minimum and maximum operating junction temperatures for the WM8351 are quoted in
Section 5. The maximum junction temperature is 125°C. Therefore, the junction temperature in the
above example is within the operating limits of the WM8351.
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Production Data
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at
or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical
Characteristics at the test conditions specified.
ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible to
damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage of
this device.
Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:
MSL1 = unlimited floor life at +6dB
Right Output Mixer
27k
DACR_TO_MIXOUTL
MIXOUTL_ENA
INR_MIXOUTL_VOL[2:0]
VMID_vgnd
INR_TO_MIXOUTL
27k
IN3L_TO_MIXOUTL
INL_MIXOUTL_VOL[2:0]
IN3L_MIXOUTL_VOL[2:0]
-
Left Output Mixer
-15 -> +6dB
OUT2L_VOL[5:0]
VMID_vgnd
+
-
-57 -> +6dB
OUT1R_VOL[5:0]
VMID_vgnd
+
-
OUT1L_VOL[5:0]
-57 -> +6dB
OUT1R_ZC
OUT1_VU
OUT1R_ENA
OUT1L_ZC
OUT1_VU
OUT1L_ENA
20k
50k
VMID_op
VMID_vgnd
-
50k
20k
20k
20k
OUT2L_MUTE
50k
20k
OUT1R_MUTE
20k
OUT1L_MUTE
OUT2R_INV
+
-
+
-
+
-
+
-
OUT2R_MUTE
OUT2R_INV_MUTE
10k
OUT1_FB
OUT2R_ENA
20k
50k
OUT2_FB
HPGND
HPVDD
20k
HPGND
VMID_vgnd
+
10k
HPVDD
IN3R_TO_OUT2R
OUT2R_INV_MUTE
Beep mix
-15 -> +6dB
IN3R_OUT2R_VOL[2:0]
OUT2R_ZC
OUT2_VU
OUT2R_ENA
VMID_vgnd
+
-
OUT2R_VOL[5:0]
-57 -> +6dB
+
-
OUT3_ENA
VMID_vgnd
+
-
VMID_vgnd
VMID_vgnd
VMID_op
OUT2L_ZC
OUT2_VU
OUT2L_ENA
DACL_TO_OUT3
20k
MIXOUTL_TO_OUT3
20k
MIXINL_TO_OUT3
20k
OUT4_TO_OUT3
20k
OUT3_TO_OUT4
20k
DACR_TO_OUT4
20k
DACL_TO_OUT4
20k
MIXOUTL_TO_OUT4
20k
VMID_vgnd
+
-
-57 -> +6dB
20k
MIXINR_TO_OUT4
MIXOUTR_TO_OUT4
20k
OUT4_ATTN
OUT4_ENA
HPVDD
HPGND
HPVDD
20k
20k
HPGND
HPVDD
HPGND
HPVDD
HPGND
OUT2R_ENA
20k
20k
HP_COM
Vmid o/p tie-off
OUT1R
(HPR)
Vmid o/p tie-off
OUT1L
(HPL)
Vmid o/p tie-off
OUT2R
Vmid o/p tie-off
OUT2L
Vmid o/p tie-off
OUT3
(LINEL/
VMID/
COM2)
Vmid o/p tie-off
OUT4
(LINER/
MONO/
VMID)
Production Data
WM8351
13.2 AUDIO PATHS
Figure 36 WM8351 Audio Path Diagram
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13.3 ENABLING THE AUDIO CODEC
Before the audio CODEC can be used, it must be enabled by writing to the CODEC_ENA,
SYSCLK_ENA and BIAS_ENA register bits.
ADDRESS
BIT
DEFAULT
DESCRIPTION
R12 (0Ch)
Power
Mgmt 5
12
CODEC_EN
A
LABEL
0
Master codec enable bit. Until this bit is set, all
codec registers are held in reset.
0 = All codec registers held in reset
1 = Codec registers operate normally.
R11 (0Bh)
Power
Mgmt 4
14
SYSCLK_ENA
0
CODEC SYSCLK enable
0 = disabled
1 = enabled
R8 (08h)
Power
Mgmt 1
5
BIAS_ENA
0
Enables bias to analogue audio CODEC
circuitry
0 = disabled
1 = enabled
Table 19 Enabling the Audio CODEC
Each individual part of the audio CODEC (e.g. left/right ADC, left/right DAC, each analogue output
pin, mic bias etc.) also has its own enable bit, which must be set before that part of the CODEC can
be used. These enable bits are described in the sections that follow.
In order to minimize output pop and click noise, it is recommended that the WM8351 device is
powered up and down under control using the following sequences:
Power Up:
w
1.
Ensure the CODEC power supplies are available before the CODEC is enabled
R12[CODEC_ENA]=1 . The order in which this is done should be DCVDD, DBVDD then
HPAVVD And/Or AVDD
2.
Mute all outputs
3.
Enable the anti-pop circuits by setting ANTI_POP. There are three Anti-pop setting options.
Recommended value is ANTI_POP = 01.
4.
Ensure external capacitors are full discharged on all outputs that are used by delaying 250ms
5.
Set the mixers and DAC volume to required settings
6.
Enable VMID by setting VMID_ENA = 1. VMID should raise in a controlled fashion and charge
the output capacitors
7.
Wait approx 500ms to allow VMID to charge.
8.
Disable the anti-pop circuits by setting ANTI_POP = 00.
9.
Un-mute all outputs
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Power Down:
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1.
Mute all outputs
2.
Enable anti-pop circuits by setting ANTI_POP to the appropriate value.
3.
Disable circuits down-stream on outputs
4.
Disable VMID by setting VMID_ENA = 0
5.
Wait for VMID to discharge (typically 500ms)
6.
Disable the anti-pop circuits by setting ANTI_POP = 00
7.
Disable all outputs
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13.4 INPUT SIGNAL PATH
The WM8351 has multiple analogue inputs. There are two input channels, Left and Right, each of
which consists of an input PGA stage followed by a boost/mix stage switch into the hi-fi ADC. Each
input PGA path has three input pins which can be configured in a variety of ways to accommodate
single-ended, differential or dual differential microphones. There are two auxiliary input pins which
can be fed into to the input boost/mix stage as well as driving into the output path. A bypass path
exists from the output of the boost/mix stage into the output left/right mixers.
13.4.1
MICROPHONE INPUTS
The microphone inputs of the WM8351 are designed to accommodate electret condenser
microphones or analogue line-in signals. They comprise the following pins:
•
IN1LP: first non-inverting input, left channel
•
IN2L: second non-inverting input, left channel
•
IN1LN: inverting input, left channel
•
IN1RP: first non-inverting input, right channel
•
IN2R: second non-inverting input, right channel
•
IN1RN: inverting input, right channel
The non-inverting inputs have constant input impedance to VMID, whereas the inverting input’s
impedance varies with the pre-amplifier’s gain. (Note: the terms “inverting” and “non-inverting” refer
to the microphone pre-amplifiers only. For overall behaviour, the inverting record mixer and the ADC,
whose output can optionally be inverted in the digital domain, must also be taken into account.)
Each channel has a programmable pre-amplifier, which supports single-ended or
pseudo-differentially connected microphones. The amplified signal for each channel can be digitised
in the audio ADC and/or mixed into the output signal path.
Figure 37 Microphone Inputs and Pre-amplifiers
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13.4.2
ENABLING THE PRE-AMPLIFIERS
ADDRESS
BIT
R9 (09h)
Power Mgmt
2
LABEL
DEFAULT
DESCRIPTION
8
INL_ENA
0
Left input PGA enable
0 = disabled
1 = enabled
9
INR_ENA
0
Right input PGA enable
0 = disabled
1 = enabled
R80 (50h)
Left Input
Volume
15
INL_ENA
0
Left input PGA enable
0 = disabled
1 = enabled
R81 (51h)
Right Input
Volume
15
INR_ENA
0
Right input PGA enable
0 = disabled
1 = enabled
Note: These bits can be accessed through R9 or through R80/R81. Reading from or writing to either
register location has the same effect.
Table 20 Enabling the Microphone Pre-amplifiers
13.4.3
SELECTING INPUT SIGNALS
ADDRESS
R72 (48h)
Mic Input
Control
BIT
LABEL
DEFAULT
0
IN1LP_ENA
1
Connect IN1LP pin to left channel input PGA
amplifier positive terminal.
0 = IN1LP not connected to input PGA
1 = input PGA amplifier positive terminal
connected to IN1LP (constant input
impedance)
DESCRIPTION
1
IN1LN_ENA
1
Connect IN1LN pin to left channel input PGA
negative terminal.
0 = IN1LN not connected to input PGA
1 = IN1LN connected to input PGA amplifier
negative terminal.
2
IN2L_ENA
0
Connect IN2L pin to left channel input PGA
amplifier
0 = IN2L not connected to input PGA amplifier
1 = IN2L connected to input PGA amplifier
8
IN1RP_ENA
1
Connect IN1RP pin to right channel input PGA
amplifier positive terminal.
0 = IN1RP not connected to input PGA
1 = right channel input PGA amplifier positive
terminal connected to IN1RP (constant input
impedance)
9
IN1RN_ENA
1
Connect IN1RN pin to right channel input PGA
negative terminal.
0 = IN1RN not connected to input PGA
1 = IN1RN connected to right channel input
PGA amplifier negative terminal.
10
IN2R_ENA
0
Connect IN2R pin to right channel input PGA
0 = IN2R not connected to input PGA amplifier
1 = IN2R connected to input PGA amplifier
Table 21 Selecting Input Pins for the Microphone Pre-amplifiers
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13.4.4
CONTROLLING THE PRE-AMPLIFIER GAINS
The gain of each microphone pre-amplifier is controlled by writing to the appropriate control registers.
The gain of each pre-amplifier applies to all three inputs associated with that pre-amplifier, whether
inverting or non-inverting. Although the gain settings for each pre-amplifier are in two separate
registers, both gains can be changed simultaneously using the IN_VU bit (see Table 22).
Additionally, it is also possible to control the gain updates to occur when the respective signal
crosses through zero. This feature reduces clicking noise caused by gain changes.
ADDRESS
R80 (50h)
Left Input
Volume
R81 (51h)
Right Input
Volume
BIT
LABEL
DEFAULT
14
INL_MUTE
0
Mute control for left channel input PGA:
0 = Input PGA not muted, normal operation
1 = Input PGA muted (and disconnected from
the following input record mixer).
DESCRIPTION
13
INL_ZC
0
Left channel input PGA zero cross enable:
0 = Update gain when gain register changes
1 = Update gain on 1st zero cross after gain
register write.
8
IN_VU
0
Input left PGA and input right PGA volume do
not update until a 1 is written either IN_VU
register bit.
7:2
INL_VOL
[5:0]
14
INR_MUTE
0
Mute control for right channel input PGA:
0 = Input PGA not muted, normal operation
1 = Input PGA muted (and disconnected from
the following input record mixer).
13
INR_ZC
0
Right channel input PGA zero cross enable:
0 = Update gain when gain register changes
1 = Update gain on 1st zero cross after gain
register write.
8
IN_VU
0
Input left PGA and input right PGA volume do
not update until a 1 is written either IN_VU
register bit.
7:2
INR_VOL
[5:0]
01_0000
01_0000
Left channel input PGA volume
000000 = -12dB
000001 = -11.25db
.
010000 = 0dB
.
111111 = 35.25dB
Right channel input PGA volume
000000 = -12dB
000001 = -11.25db
.
010000 = 0dB
.
111111 = 35.25dB
Table 22 Controlling the Microphone Pre-amplifier Gain
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13.4.5
MICROPHONE BIASING
The WM8351 provides a programmable, low-noise bias voltage for condenser electret microphones
on the MICBIAS pin.
ADDRESS
BIT
R8 (08h)
Power Mgmt 1
4
MICB_ENA
LABEL
R74 (4Ah)
Mic Bias
Control
15
MICB_ENA
14
MICB_SEL
DEFAULT
DESCRIPTION
0
Microphone bias enable
0 = OFF (high impedance output)
1 = ON
This bit can be accessed through R8 or
through R74. Reading from or writing to
either register location has the same effect.
0
Microphone bias voltage control:
0 = 0.9 * AVDD
1 = 0.75 * AVDD
Note: MICB_ENA can be accessed through R8 or through R74. Reading from or writing to either
register location has the same effect.
Table 23 Controlling the Microphone Bias Voltage
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13.4.6
AUXILIARY INPUTS (IN3L AND IN3R)
The WM8351 provides two additional analogue input pins, IN3L and IN3R, for line-level audio or
“beep” signals. Each pin has a simple input buffer whose output signal can be digitised in the audio
ADC and/or mixed into the output signal path. The Right input IN3R may also be connected to the
Output Beep Mixer, for output on OUT2R (see Table 43). The input buffers have a nominal default
gain of -1 (0dB).
IN3L_SHORT, R73[6]
20k
IN3L
To:
Left Input Mixer,
Left Output Mixer
+
20k
Vmid
IN3R_SHORT, R73[14]
20k
IN3R
To:
Right Input Mixer,
Right Output Mixer,
Output Beep Mixer
+
20k
Vmid
Figure 38 Auxiliary Input Buffers
REGISTER
ADDRESS
BIT
R9 (09h)
Power
Mgmt 2
10
IN3L_ENA
0
IN3L Amplifier enable
0 = disabled
1 = enabled
11
IN3R_ENA
0
IN3R Amplifier enable
0 = disabled
1 = enabled
7
IN3L_ENA
0
IN3L Amplifier enable
0 = disabled
1 = enabled
15
IN3R_ENA
0
IN3R Amplifier enable
0 = disabled
1 = enabled
6
IN3L_SHORT
0
Short circuit internal input resistor for
IN3L amplifier.
0 = Internal resistor in circuit
1 = Internal resistor shorted
14
IN3R_SHORT
0
Short circuit internal input resistor for
IN3R amplifier.
0 = Internal resistor in circuit
1 = Internal resistor shorted
R73 (49h)
IN3 Input
Control
LABEL
DEFAULT
DESCRIPTION
Note: IN3L_ENA and IN3R_ENA can be accessed through R9 or through R73. Reading from or
writing to either register location has the same effect.
Table 24 Controlling the Auxiliary Input Buffers
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13.4.7
INPUT MIXERS
The WM8351 has mixers in the input signal paths. This allows each ADC to record either a single
input signal or a mix of several signals, as desired. The gain for the different input signals can also
be adjusted. Each record mixer has four inputs:
•
the output of the respective (left/right) microphone pre-amplifier
•
the IN2L and IN2R pins (used as a line input, bypassing the microphone pre-amplifiers)
•
the output of the respective (left/right) auxiliary input buffer (ie. inputs IN3L or IN3R)
•
the output of the OUT4 amplifier (only one input mixer at a time can take this signal)
Figure 39 Input Mixers
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ADDRESS
R9 (09h)
Power Mgmt
2
R98 (62h)
Input mixer
volume for left
channel
R99 (63h)
Input mixer
volume for
right channel
R100 (64h)
OUT4 Mixer
Control
BIT
LABEL
DEFAULT
DESCRIPTION
7
MIXINR_ENA
0
Right input mixer enable
0 = disabled
1 = enabled
6
MIXINL_ENA
0
Left input mixer enable
0 = disabled
1 = enabled
0
INL_MIXINL_V
OL
0
Boost enable for left channel input PGA:
0 = PGA output has +0dB gain through
input record mixer.
1 = PGA output has +20dB gain through
input record mixer.
3:1
IN2L_MIXINL_
VOL [2:0]
000
IN2L amplifier volume control to right input
mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
11:9
IN3L_MIXINL_
VOL
000
IN3L amplifier volume control to right input
mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
0
INR_MIXINR_
VOL
1
Boost enable for right channel input PGA:
0 = PGA output has +0dB gain through
input record mixer.
1 = PGA output has +20dB gain through
input record mixer.
7:5
IN2R_MIXINR_
VOL [2:0]
000
IN2R amplifier volume control to right
input mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
15:13
IN3R_MIXINR_
VOL [2:0]
000
IN3R amplifier volume control to right
input mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
15
OUT4_MIXIN_
DST
0
3:1
OUT4_MIXIN_
VOL [2:0]
000
Select routing of OUT4 to input mixers.
0 = OUT4 to left input mixer.
1 = OUT4 to right input mixer.
Controls the gain of OUT4 to left and right
input mixers:
000 = Path disabled (left and right mute)
001 = -12dB gain through boost stages
010 = -9dB gain through boost stages
….
111 = +6dB gain through boost stages
Table 25 Input Mixer Control
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13.5 ANALOGUE TO DIGITAL CONVERTER (ADC)
The high-performance stereo ADC within the WM8351 converts analogue input signals to the digital
domain. It uses a multi-bit, over-sampled sigma-delta architecture. The ADC’s over-sampling rate is
selectable to control the trade-off between best audio performance and lowest power consumption. A
variety of digital filtering stages process the ADC’s digital output signal before it is sent to the
WM8351 audio interface. These include:
•
digital decimation and filtering needed for the ADC
•
digital volume control
•
A programmable high-pass filter
The audio ADC supports all commonly used audio sampling rates between 8kHz and 48kHz (see
Figure 40).
Figure 40 ADC Digital Filter Path
ADDRESS
BIT
R11 (0Bh)
Power Mgmt 4
2
DEFAULT
DESCRIPTION
ADCL_ENA
R66 (42h)
ADC Digital
Volume L
15
R11 (0Bh)
Power Mgmt 4
3
R67 (43h)
ADC Digital
Volume R
15
R64 (40h)
ADC Control
LABEL
0
Left ADC enable
0 = disabled
1 = enabled
When ADCR and ADCL are used
together as a stereo pair, then both
ADCs must be enabled together using
a single register write to Register R11
(0Bh).
ADCR_ENA
0
Right ADC enable
0 = disabled
1 = enabled
When ADCR and ADCL are used
together as a stereo pair, then both
ADCs must be enabled together using
a single register write to Register R11
(0Bh).
1
ADCL_DATINV
0
ADC Left channel polarity:
0 = Normal
1 = Inverted
0
ADCR_DATINV
0
ADC Right Channel Polarity
0 = Normal
1 = Inverted
Note: ADCL_ENA and ADCR_ENA can be accessed through R11 or through R66/R67. Reading
from or writing to either register location has the same effect.
Table 26 Enabling the ADC Left and Right Channels
When ADCR and ADCL are used together as a stereo pair, then it is important that ADCR_ENA and
ADCL_ENA are enabled at the same time using a single register write. This must be implemented by
writing to the bits in Register R11 (0Bh). This ensures that the system starts up both channels in a
synchronous manner.
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13.5.1
ADC VOLUME CONTROL
Programmable digital volume control is provided to attenuate the ADC’s output signal.
ADDRESS
BIT
R66 (42h)
ADC Digital
Volume L
8
7:0
R67 (43h)
ADC Digital
Volume R
8
7:0
LABEL
ADC_VU
ADCL_VO
L [7:0]
DESCRIPTION
0
ADC left and ADC right volume do not update
until a 1 is written to either ADC_VU register
bit.
1100_0000
ADC_VU
ADCR_VO
L [7:0]
DEFAULT
0
1100_0000
Left ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -71.625dB
0000 0010 = -71.25dB
... 0.375dB steps up to
1110 1111 = +17.625dB
ADC left and ADC right volume do not update
until a 1 is written to either ADC_VU register
bit.
Right ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -71.625dB
0000 0010 = -71.25dB
... 0.375dB steps up to
1110 1111 = +17.625dB
Table 27 ADC Volume Control
13.5.2
ADC HIGH-PASS FILTER
A digital high-pass filter is provided to remove DC offsets from the ADC signal.
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R11 (0Bh)
Power
Mgmt 4
13
ADC_HPF_EN
A
0
R64 (40h)
ADC
Control
15
High Pass Filter enable
0 = disabled
1 = enabled
This bit can be accessed through R11 or
through R64. Reading from or writing to either
register location has the same effect.
ADC_HPF_CU
T [1:0]
00
Select cut-off frequency for high-pass filter
00 = 2^-11 (first order) = 3.7Hz @
fs=44.1kHz
01 = 2^-5 (2nd order) = ~250Hz @ fs=8kHz
10 = 2^-4 (2nd order) = ~250Hz @ fs=16kHz
11 = 2^-3 (2nd order) = ~250Hz @ fs=32kHz
9:8
Note: ADC_HPF_ENA can be accessed through R11 or through R64. Reading from or writing to
either register location has the same effect.
Table 28 Controlling the ADC High-pass Filter
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13.6 DIGITAL MIXING
13.6.1
DIGITAL SIDETONE
A digital sidetone is available when ADCs and DACs are operating at the same sample rate. Digital
data from either left or right ADC can be mixed with the audio interface data on the left and right DAC
channels. Sidetone data is taken from the ADC high pass filter output, to reduce low frequency noise
in the sidetone (e.g. wind noise or mechanical vibration).
The digital sidetone will not function when ADCs and DACs are operating at different sample rates.
When using the digital sidetone, it is recommended that the ADCs are enabled before un-muting the
DACs to prevent pop noise. The DAC volumes and sidetone volumes should be set to an appropriate
level to avoid clipping at the DAC input.
The digital sidetone is controlled as shown Table 29.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R68 (44h)
ADC
Divider
11:8
ADCL_DAC_SVOL
[3:0]
0000
Left Digital Side tone Volume in dB
(See Table 30 for volume range)
7:4
ADCR_DAC_SVOL
[3:0]
0000
Right Digital Side tone Volume in dB
(See Table 30 for volume range)
R60 (3Ch)
Digital Side
Tone
Control
13:12
ADC_TO_DACL
[1:0]
00
DAC Left Side-tone Control
11 = Unused
10 = Mix ADCR into DACL
01 = Mix ADCL into DACL
00 = No Side-tone mix into DACL
11:10
ADC_TO_DACR
[1:0]
00
DAC Right Side-tone Control
11 = Unused
10 = Mix ADCR into DACR
01 = Mix ADCL into DACR
00 = No Side-tone mix into DACR
Table 29 Digital Side Tone Control
The coding of ADCL_DAC_SVOL and ADCR_DAC_SVOL is described in Table 30.
ADCL_DAC_SVOL or
ADCR_DAC_SVOL
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
SIDETONE
VOLUME
-36
-33
-30
-27
-24
-21
-18
-15
-12
-9
-6
-3
0
0
0
0
Table 30 Digital Side Tone Control
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13.7 DIGITAL TO ANALOGUE CONVERTER (DAC)
The WM8351 contains a high-performance stereo DAC to convert digital audio signals to the
analogue domain. Audio data is passed to the WM8351 via the audio interface, and passes through
a variety of digital filtering stages before reaching the DAC. These include:
•
Digital volume control
•
Digital filtering, interpolation and sigma-delta modulation functions needed for the DAC
The audio DAC supports all commonly used audio sampling rates between 8kHz and 48kHz.
Figure 41 DAC Overview
BIT
LABEL
DEFAULT
R11 (0Bh)
Power Mgmt
4
ADDRESS
4
DACL_EN
A
0
Left DAC enable
0 = disabled
1 = enabled
DESCRIPTION
R50 (32h)
DAC Digital
Volume Left
15
R11 (0Bh)
Power Mgmt
4
5
DACR_EN
A
0
Right DAC enable
0 = disabled
1 = enabled
R51 (33h)
DAC Digital
Volume Right
15
Note: These bits can be accessed through R11 or through R50/R51. Reading from or writing to
either register location has the same effect.
Table 31 DAC Enable
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13.7.1
DAC PLAYBACK VOLUME CONTROL
REGISTER
ADDRESS
R50 (32h)
DAC Digital
Volume Left
BIT
8
7:0
R51 (33h)
DAC Digital
Volume Right
8
7:0
LABEL
DAC_VU
DACL_VOL
[7:0]
DAC_VU
DACR_VOL
[7:0]
DEFAULT
0
1100_0000
0
1100_0000
DESCRIPTION
DAC left and DAC right volume do not
update until a 1 is written to either
DAC_VU register bit.
Left DAC digital volume control:
0000_0000 = Digital mute
0000_0001 = -71.625dB
0000_0010 = -71.25dB
… (0.375dB steps)
1100_000 = 0dB
DAC left and DAC right volume do not
update until a 1 is written to either
DAC_VU register bit.
Right DAC digital volume control:
0000_0000 = Digital mute
0000_0001 = -71.625dB
0000_0010 = -71.25dB
… (0.375dB steps)
1100_000 = 0dB
Table 32 DAC Volume Control
13.7.2
DAC SOFT MUTE AND SOFT UN-MUTE
The WM8351 has a soft mute function which, when enabled, gradually attenuates the volume of the
DAC output. When soft mute is disabled, the gain will either gradually ramp back up to the digital
gain setting, or return instantly to the digital gain setting, depending on the DAC_MUTEMODE
register bit.
The DAC is soft-muted by default (DAC_MUTE = 1). To play back an audio signal, this function must
first be disabled by setting DAC_MUTE to 0.
Soft Mute Mode would typically be enabled (DAC_MUTEMODE = 1) when using DAC_MUTE during
playback of audio data so that when DAC_MUTE is subsequently disabled, the sudden volume
increase will not create pop noise by jumping immediately to the previous volume level (e.g.
resuming playback after pausing during a track).
Soft Mute Mode would typically be disabled (DAC_MUTEMODE = 0) when un-muting at the start of a
music file, in order that the first part of the track is not attenuated (e.g. when starting playback of a
new track, or resuming playback after pausing between tracks).
DAC muting and un-muting using
volume control bits DACL_VOL and
DACR_VOL.
DAC muting and un-muting using soft
mute bit DAC_MUTE. Soft un-mute
not enabled (DAC_MUTEMODE = 0).
DAC muting and un-muting using soft
mute bit DAC_MUTE. Soft un-mute
enabled (DAC_MUTEMODE = 1).
Figure 42 DAC Mute Control
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The volume ramp rate during soft mute and un-mute is controlled by the DAC_MUTERATE bit.
Ramp rates of fs/32 and fs/2 are selectable as shown
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R58 (3Ah)
DAC Mute
14
DAC_MUTE
1
DAC Mute
0 = disabled
1 = enabled
R59 (3Bh)
DAC Mute
Volume
14
DAC_MUTEM
ODE
0
DAC Soft Mute Mode
0 = Disabling soft-mute
(DAC_MUTE=0) will cause the volume
to change immediately to the
DACL_VOL / DACR_VOL settings
1 = Disabling soft-mute
(DAC_MUTE=0) will cause the volume
to ramp up gradually to the DACL_VOL
/ DACR_VOL settings
13
DAC_MUTER
ATE
0
DAC Soft Mute Ramp Rate
0 = Fast ramp (24kHz at fs=48k,
providing maximum delay of 10.7ms)
1 = Slow ramp (1.5kHz at fs=48k,
providing maximum delay of 171ms)
Table 33 DAC Soft-Mute Control
13.7.3
DAC DE-EMPHASIS
Digital de-emphasis can be applied to the DAC playback data (e.g. when the data comes from a CD
with pre-emphasis used in the recording). De-emphasis filtering is available for sample rates of
48kHz, 44.1kHz and 32kHz.
REGISTER
ADDRESS
BIT
R48 (30h)
DAC Control
5:4
LABEL
DEEMP [1:0]
DEFAULT
00
DESCRIPTION
De-Emphasis Control
11 = 48kHz sample rate
10 = 44.1kHz sample rate
01 = 32kHz sample rate
00 = No de-emphasis
Table 34 DAC De-Emphasis Control
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13.7.4
DAC OUTPUT PHASE AND MONO MIXING
The digital audio data is converted to oversampled bit streams in the on-chip 24-bit digital
interpolation filters. The bitstream data enters two multi-bit, sigma-delta DACs, which convert them to
high quality analogue audio signals. The multi-bit DAC architecture reduces high frequency noise and
sensitivity to clock jitter. It also uses a Dynamic Element Matching technique for high linearity and
low distortion.
In normal operation, the left and right channel digital audio data is converted to analogue in two
separate DACs. It is also possible for the DACs to output a mono mix of left and right channels,
using DAC_MONO. Both DACs must be enabled for this mono mix to function.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R48 (30h) DAC
Control
13
DAC_MONO
0
Adds left and right channel and
halves the resulting output to
create a mono output
1
DACL_DATINV
0
DAC data left channel polarity
0 = Normal
1 = Inverted
0
DACR_DATINV
0
DAC data right channel polarity
0 = Normal
1 = Inverted
Table 35 DAC Mono Mix and Phase Invert Select
13.7.5
DAC STOPBAND ATTENUATION
The DAC digital filter type is selected by the DAC_SB_FILT register bit as shown in Table 36.
REGISTER
ADDRESS
R59 (3Bh)
DAC Digital
Control
BIT
12
LABEL
DAC_SB_FILT
DEFAULT
0
DESCRIPTION
Selects DAC filter characteristics
0 = Normal mode
1 = Sloping stopband mode
Table 36 DAC Filter Selection
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13.8 OUTPUT SIGNAL PATH
The analogue output pins produce audio signals to drive headphones, line-out connections and/or
external loudspeaker amplifiers. These pins include:
•
OUT1L and OUT1R
•
OUT2L and OUT2R
•
OUT3 and OUT4
OUT1L, OUT1R, OUT2L and OUT2R have individual analogue volume PGAs with -57dB to +6dB
ranges. AC-coupled and Capless headphone drive modes are available. Common mode noise
rejection is possible using the HPCOM connection.
OUT3 and OUT4 can be configured as a stereo line out (OUT3 is left output and OUT4 is right
output). OUT3 and OUT4 can also be used as a Vmid buffer to provide a “ground” reference for
headphone outputs, eliminating the need for DC blocking capacitors.
Alternatively, OUT4 can be used to provide a mono mix of left and right channels.
All analogue output pins are powered through the HPVDD and HPGND pins.
Each output can drive a headphone load down to 16Ω.
There are four output mixers in the output signal path: the left and right channel mixers which control
the signals to headphone (and optionally the line outputs) and also dedicated OUT3 and OUT4
mixers.
13.8.1
ENABLING THE ANALOGUE OUTPUTS
Each output can be individually enabled or disabled via dedicated control bits.
ADDRESS
BIT
R10 (0Ah)
0
R104 (68h)
15
R10 (0Ah)
1
R105 (69h)
15
R10 (0Ah)
2
R106 (70h)
15
R10 (0Ah)
3
R107 (71h)
15
R9 (09h)
4
R92 (5Ch)
15
R9 (09h)
5
R93 (5Dh)
15
LABEL
DEFAULT
DESCRIPTION
OUT1L_ENA
0
OUT1L enable
0 = disabled
1 = enabled
OUT1R_ENA
0
OUT1R enable
0 = disabled
1 = enabled
OUT2L_ENA
0
OUT2L enable
0 = disabled
1 = enabled
OUT2R_ENA
0
OUT2R enable
0 = disabled
1 = enabled
OUT3_ENA
0
OUT3 enable
0 = disabled
1 = enabled
OUT4_ENA
0
OUT4 enable
0 = disabled
1 = enabled
Note: Each bit can be accessed through two separate control registers. Reading from or writing to
either register location has the same effect.
Table 37 Enabling the Analogue Outputs
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13.8.2
OUTPUT MIXERS
The left and right output channel mixers are shown in Figure 43. These mixers allow the AUX inputs,
the ADC bypass and the DAC left and right channels to be combined as desired. This allows a mono
mix of the DAC channels to be done as well as mixing in external line-in from the IN3.
The IN3L/IN3R and PGA inputs have individual volume control from -15dB to +6dB. The DAC
channel volumes can be adjusted in the digital domain if required. The outputs of these mixers are
routed to OUT1L/OUT1R or OUT2L/OUT2R. They can also optionally be routed to the OUT3 and
OUT4 mixers.
Figure 43 Output Mixers
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Each output mixer can be enabled or disabled by writing either to the power management control
register or to the respective mixer’s own control register. Each analogue signal going into the output
mixers can be independently enabled or muted for each mixer.
ADDRESS
R88 (58h)
Left Mixer
Control
BIT
LABEL
DEFAULT
0
INL_TO_MIXOU
TL
0
Left input PGA output to left output
mixer
0 = not selected
1 = selected
DESCRIPTION
1
INR_TO_MIXOU
TL
0
Right input PGA output to left output
mixer
0 = not selected
1 = selected
2
IN3L_TO_MIXO
UTL
0
IN3L amplifier output to left channel
output mixer:
0 = not selected
1 = selected
11
DACL_TO_MIX
OUTL
0
Left DAC output to left output mixer
0 = not selected
1 = selected
12
DACR_TO_MIX
OUTL
0
Right DAC output to left output mixer
0 = not selected
1 = selected
15
MIXOUTL_ENA
0
Left output channel mixer enable
0 = disabled
1 = enabled
R9 (09h)
Power Mgmt 2
0
R89 (59h)
Right Mixer
Control
0
INL_TO_MIXOU
TR
0
Left input PGA output to right output
mixer
0 = not selected
1 = selected
1
INR_TO_MIXOU
TR
0
Right input PGA output to right
output mixer
0 = not selected
1 = selected
3
IN3L_TO_MIXO
UTR
0
IN3L amplifier output to left channel
output mixer:
0 = not selected
1 = selected
11
DACL_TO_MIX
OUTR
0
Left DAC output to right output mixer
0 = not selected
1 = selected
12
DACR_TO_MIX
OUTR
0
Right DAC output to right output
mixer
0 = not selected
1 = selected
15
MIXOUTR_ENA
0
Right Output Mixer Enable
0 = disabled
1 = enabled
R9 (09h)
Power Mgmt 2
1
Note: MIXOUTL_ENA and MIXOUTR_ENA can be accessed through two separate control
registers. Reading from or writing to either register location has the same effect.
Table 38 Selecting Signals into the Output Mixers
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The gain for microphone pre-amp and auxiliary input (IN3L/IN3R) signals can be independently
adjusted for each output mixer. This does not affect the volume of the same signals going into the
separate record mixer. The level of the DAC output signals can be adjusted using the DAC’s digital
volume control function (see Table 32).
ADDRESS
R96 (60h)
Output Left
Mixer
Volume
R97 (61h)
Output Right
Mixer
Volume
BIT
LABEL
DEFAULT
3:1
INL_MIXOUTL_VOL
[2:0]
000
Left input PGA volume control to left
output mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
DESCRIPTION
7:5
INR_MIXOUTL_VO
L [2:0]
000
Right input PGA volume control to left
output mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
11:9
IN3L_MIXOUTL_VO
L [2:0]
000
IN3L amplifier volume control to left
output mixer
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
3:1
INL_MIXOUTR_VO
L [2:0]
000
Left input PGA volume control to right
output mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
7:5
INR_MIXOUTR_VO
L [2:0]
000
Right input PGA volume control to
right output mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
15:13
IN3R_MIXOUTR_V
OL [2:0]
000
IN3R amplifier volume control to right
output mixer.
000 = Path disabled (disconnected)
001 = -12dB gain through mixer
010 = -9dB gain through mixer
…
111 = +6dB gain through mixer
Table 39 Controlling the Gain of Signals Going into the Output Mixers
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13.9 ANALOGUE OUTPUTS
13.9.1
OUT1L AND OUT1R
The headphone outputs, OUT1L and OUT1R can drive a 16Ω or 32Ω headphone load, either through
DC blocking capacitors, or DC coupled without any capacitor. Each output has an analogue volume
control PGA with a gain range of -57dB to +6dB as shown in Figure 44.
Common mode noise rejection is also possible on the OUT1L and OUT1R outputs, using HPCOM as
the return path. The HPCOM feature must be enabled via the OUT1_FB register field and the
HPCOM connection must be AC coupled to the headphone output. A 4.7uF coupling capacitor is
required between the noisy ground connection the HPCOM pin.
The control register fields for the OUT1L and OUT1R outputs are described in Table 40. The
available output configurations are shown in Section 13.9.3.
OUT1L_MUTE
R104 [14]
From left
output mixer
-1
OUT1L
OUT1L_VOL
R104 [7:2]
OUT1R_MUTE
R105 [14]
From right
output mixer
-1
OUT1R
OUT1R_VOL
R105 [7:2]
HPCOM
Vmid
OUT1_FB
R76 [0]
Figure 44 Headphone Outputs OUT1L and OUT1R
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ADDRESS
R104 (68h)
OUT1L
Volume
R105 (69h)
OUT1R
Volume
BIT
DEFAULT
DESCRIPTION
OUT1L_MUTE
0
OUT1L mute:
0 = normal operation
1 = mute
13
OUT1L_ZC
0
OUT1L volume zero cross enable
0 = Change gain immediately
1 = Change gain on zero cross only
8
OUT1_VU
0
OUT1L and OUT1R volumes do not
update until a 1 is written to either
OUT1_VU.
7:2
OUT1L_VOL
[5:0]
14
OUT1R_MUTE
0
OUT1R mute:
0 = normal operation
1 = mute
13
OUT1R_ZC
0
OUT1R volume zero cross enable
0 = Change gain immediately
1 = Change gain on zero cross only
8
OUT1_VU
0
OUT1L and OUT1R volumes do not
update until a 1 is written to either
OUT1_VU.
7:2
R76 (4Ch)
Output
Control
LABEL
14
0
OUT1R_VOL
[5:0]
OUT1_FB
11_1001
11_1001
0
OUT1L volume:
000000 = -57dB
...
111001 = 0dB
...
111111 = +6dB
OUT1R volume:
000000 = -57dB
...
111001 = 0dB
...
111111 = +6dB
Enable Headphone common mode
ground feedback for OUT1
0 = disabled (HPCOM unused)
1 = enabled (common mode feedback
through HPCOM)
Table 40 Controlling OUT1L and OUT1R
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13.9.2
OUT2L AND OUT2R
OUT2L and OUT2R are designed as a stereo pair and can drive a headphone, a line load or a
loudspeaker amplifier. Each output has an analogue volume control PGA with a gain range of -57dB
to +6dB as shown in Figure 45.
Common mode noise rejection is also possible on the OUT2L and OUT2R outputs, using HPCOM as
the return path. The HPCOM feature must be enabled via the OUT2_FB register field and the
HPCOM connection must be AC coupled to the headphone output. A 4.7uF coupling capacitor is
required between the noisy ground connection the HPCOM pin.
The signal path from the right output mixer to OUT2R can be inverted, using the OUT2R_INV and
OUT2R_INV_MUTE register bits. Table 41 describes the required settings of these register bits for
inverted and non-inverted configurations. Note that the OUT2R_MUTE mutes the OUT2R signal path
in both cases.
OUT2R_INV
OUT2R_INV_MUTE
0
1
Non-inverting path from MIXOUTR to OUT2R
DESCRIPTION
1
0
Inverting path from MIXOUTR to OUT2R
Table 41 OUT2R Signal Path Polarity
The control register fields for the OUT2L and OUT2R outputs are described in Table 42. The
available output configurations are shown in Section 13.9.3.
OUT2L_MUTE
R106 [14]
From left
output mixer
-1
OUT2L
OUT2L_VOL
R106 [7:2]
OUT2R_MUTE
R107 [14]
From right
output mixer
-1
OUT2R
OUT2R_VOL
R107 [7:2]
HPCOM
Vmid
OUT2_FB
R76 [2]
Figure 45 Headphone Outputs OUT2L and OUT2R
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ADDRESS
BIT
LABEL
DEFAULT
R106 (6Ah)
for OUT2L
Volume
14
OUT2L_MU
TE
0
OUT2L mute:
0 = normal operation
1 = mute
13
OUT2L_ZC
0
OUT2L volume zero cross enable
0 = Change gain immediately
1 = Change gain on zero cross only
8
OUT2_VU
0
OUT2L and OUT2R volumes do not update
until a 1 is written to either OUT2_VU register
bits.
R107 (6Bh)
for OUT2R
R76 (4Ch)
Output
Control
DESCRIPTION
7:2
OUT2L_VO
L [5:0]
11_1001
14
OUT2R_M
UTE
0
OUT2R mute:
0 = normal operation
1 = mute
13
OUT2R_ZC
0
OUT2R volume zero cross enable
0 = Change gain immediately
1 = Change gain on zero cross only
10
OUT2R_IN
V
0
Enable OUT2R inverting amplifier
0 = disabled
1 = enabled
This register must be set to 0 when using the
non-inverting MIXOUT2R to OUT2R path.
This register must be set to 1 when using the
inverting MIXOUT2R to OUT2R path.
9
OUT2R_IN
V_MUTE
1
Mute output of PGA to inverting amplifier.
0 = PGA output goes to inverting amplifier
1 = PGA output goes to output driver
This register must be set to 0 when using the
inverting MIXOUT2R to OUT2R path.
This register must be set to 1 when using the
non-inverting MIXOUT2R to OUT2R path.
8
OUT2_VU
0
OUT2L and OUT2R volumes do not update
until a 1 is written to either OUT2_VU register
bits.
7:2
OUT2R_VO
L [5:0]
11_1001
2
OUT2_FB
0
OUT2L volume:
000000 = -57dB
...
111001 = 0dB
...
111111 = +6dB
OUT2R volume:
000000 = -57dB
...
111001 = 0dB
...
111111 = +6dB
Enable Headphone common mode ground
feedback for OUT2
0 = disabled (HPCOM unused)
1 = enabled (common mode feedback through
HPCOM)
Table 42 Controlling OUT2L and OUT2R
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A beep signal on the IN3R pin (see Table 43) can be mixed into OUT2R independently of the right
output mixer (i.e. without mixing the same beep signal into OUT1R).
Note that this feature is only possible when the inverting path configuration (MIXOUTR to OUT2R) is
selected. See Table 41 for the required register settings.
ADDRESS
R111 (6Fh)
Beep
Volume
BIT
LABEL
DEFAULT
15
IN3R_TO_O
UT2R
0
Beep mixer enable
0 = disabled
1 = enabled
DESCRIPTION
7:5
IN3R_OUT2R
_VOL [2:0]
000
Beep mixer volume:
000 = -15dB
… in +3dB steps
111 = +6dB
Table 43 Controlling the “Beep” Path (IN3R to OUT2R)
13.9.3
HEADPHONE OUTPUTS EXTERNAL CONNECTIONS
Some example headphone output configurations are shown below.
Figure 46 AC-Coupled Headphone Drive
Figure 47 DC-Coupled (Capless) Mode
Headphone Drive
Figure 48 AC-Coupled Headphone Drive
with Common Mode Noise Rejection
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Notes:
1.
The above figures illustrate the headphone connections to outputs OUT1L and OUT1R. The
equivalent configurations apply equally to OUT2L and OUT2R.
2.
The DC-coupled configuration illustrated in Figure 47 shows OUT4 (muted) being used as the
Ground Return connection. The same capability may alternatively be provided using OUT3.
3.
Twin headphone output (OUT1L, OUT1R, OUT2L and OUT2R) is possible, using a shared
Ground Return connection via any of OUT3, OUT4, HPCOM or AGND.
4.
Capless operation is not possible when using the HPCOM feature.
When DC blocking capacitors are used their capacitance and the load resistance together determine
the lower cut-off frequency, fc. Increasing the capacitance lowers fc, improving the bass response.
Smaller capacitance values will diminish the bass response. For a 16Ω load and a capacitance of
220μF, the following derivation of cut-off frequency applies:
fc = 1 / 2π RLC1 = 1 / (2π x 16Ω x 220μF) = 45 Hz
In the DC coupled configuration, the headphone “ground” is connected to VMID. The OUT3 or OUT4
pins can be configured as DC output drivers by de-selecting all inputs to the OUT3 or OUT4 mixers.
The DC voltage on VMID in this configuration is equal to the DC offset on the OUT1L and OUT2L
pins therefore no DC blocking capacitors are required. This saves space and material cost in
portable applications.
It is recommended to only use the DC coupled configuration to drive headphones, and not to use this
configuration to drive the line input of another device.
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13.9.4
OUT3 AND OUT4
The additional analogue outputs OUT3 and OUT4 have independent mixers and can be used in a
number of different ways:
•
OUT3 and OUT4 as a stereo pair (OUT3 = left, OUT4 = right) to drive a headphone or line load
•
OUT3 or OUT4 as pseudo-ground outputs for headphones connected directly (without DC
blocking capacitors) to OUT1L/OUT1R or OUT2L/OUT2R
•
OUT4 as a mono mix of left and right signals
The OUT3 and OUT4 output stages are powered from HPVDD and HPGND.
If OUT4 is providing a mono mix, it is recommended to reduce the level of OUT4 by 6dB to avoid
clipping in the event of 2 full-scale signals being combined. This is implemented via the OUT4_ATT
register field. When OUT4_ATT is asserted, then OUT4 = (L+R) / 2.
Figure 49 OUT 3 and OUT4 Mixers
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OUT3 can provide a buffered midrail headphone pseudo-ground, or a left line output. It can also be
a common mode input for OUT2L/OUT2R. OUT4 can provide a buffered midrail headphone pseudoground, a right line output, or a mono mix output. It can also be mixed into the input boost mixer for
recording.
ADDRESS
R92 (5Ch)
OUT3 Mixer
BIT
LABEL
DEFAULT
DESCRIPTION
11
DACL_TO_OUT3
0
Left DAC output to OUT3
0 = disabled
1 = enabled
8
MIXINL_TO_OUT3
0
Left input mixer to OUT3
0 = disabled
1 = enabled
3
OUT4_TO_OUT3
0
OUT4 mixer to OUT3
0 = disabled
1 = enabled
0
MIXOUTL_TO_OUT
3
0
Left output mixer to OUT3
0 = disabled
1 = enabled
R92 (5Ch)
OUT3 Mixer
15
OUT3_ENA
0
R9 (09h)
Power Mgmt 2
4
OUT3 enable
0 = disabled
1 = enabled
Note: OUT3_ENA can be accessed through R92 or R9. Reading from or writing to either register
location has the same effect.
Table 44 Controlling the OUT3 Mixer
ADDRESS
R93 (5Dh)
OUT4 Mixer
BIT
LABEL
DEFAULT
DESCRIPTION
12
DACR_TO_OUT4
0
Right DAC output to OUT4
0 = disabled
1 = enabled
11
DACL_TO_OUT4
0
Left DAC output to OUT4
0 = Disabled
1 = Enabled
10
OUT4_ATT
0
Reduce OUT4 output by 6dB
0 = Output at normal level
1 = Output reduced by 6dB
9
MIXINR_TO_OUT4
0
Right input mixer to OUT4
0 = disabled
1 = enabled
2
OUT3_TO_OUT4
0
OUT3 mixer to OUT4
This function is not supported
1
MIXOUTR_TO OUT4
0
Right output mixer to OUT4
0 = Disabled
1 = Enabled
0
MIXOUTL_TO_OUT4
0
Left output mixer to OUT4
0 = disabled
1 = enabled
R93 (5Dh)
OUT4 Mixer
15
OUT4_ENA
0
R9 (09h)
Power Mgmt 2
5
OUT4 enable
0 = disabled
1 = enabled
Note: OUT4_ENA can be accessed through R93 or R9. Reading from or writing to either register
location has the same effect.
Table 45 Controlling the OUT4 Mixer
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13.10 DIGITAL AUDIO INTERFACE
The audio interface enables the WM8351 to exchange audio data with other system components. It
is separate from the control interface and has four dedicated pins:
•
ADCDAT: Output pin for data coming from the audio ADC
•
DACDAT: Input pin for audio data going to the audio DAC
•
LRCLK: Data Left/Right alignment clock (also known as “word clock”)
•
BCLK: Bit clock, for synchronisation
The LRCLK and BCLK pins are outputs when the WM8351 operates as a master device and are
inputs when it is a slave device.
In order to allow the ADC and DAC to run at different sampling rates, separate ADCLRCLK and
ADCBCLK signals are both available through GPIO pins: GPIO5 (ADCLRCLK) and GPIO6 or GPIO8
(ADCBCLK). This feature also allows mixed Master/Slave operation between the ADC and DAC.
13.10.1 AUDIO DATA FORMATS
The audio interface supports six different audio data formats:
•
Left justified
•
Right justified
•
I 2S
•
DSP mode A
•
DSP mode B
•
TDM Mode
In all of these formats, the MSB (most significant bit) of each data sample is transferred first and the
LSB (least significant bit) last.
ADDRESS
BIT
LABEL
DEFAULT
R112 (70h)
Audio
Interface
15
AIF_BCLK_INV
0
BCLK polarity
0 = normal
1 = inverted
DESCRIPTION
13
AIF_TRI
0
Sets Output enables for LRCLK and
BCLK and ADCDAT to inactive state
0 = normal
1 = forces pins to Hi-Z
12
AIF_LRCLK_IN
V
0
LRCLK clock polarity
0 = normal
1 = inverted
DSP Mode – mode A/B select
0 = MSB is available on 2nd BCLK rising
edge after LRCLK rising edge (mode A)
1 = MSB is available on 1st BCLK rising
edge after LRCLK rising edge (mode B)
w
11:10
AIF_WL [1:0]
10
(24 bits)
8:9
AIF_FMT [1:0]
10
Data word length
11 = 32 bits
10 = 24 bits
01 = 20 bits
00 = 16 bits
Note: When using the Right-Justified
data format (AIF_FMT=00), the
maximum word length is 24 bits.
Data format
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ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
(I2S)
R114 (72h)
Audio
Interface
ADC
Control
R115 (73h)
Audio
Interface
DAC
Control
00 = Right Justified
01 = Left Justified
10 = I2S
11 = DSP / PCM mode
Note - see Section 13.11 for the
selection of 8-bit mode.
7
AIFADC_PD
0
Enables a pull down on ADC data pin
0 = disabled
1 = enabled
6
AIFADCL_SRC
0
Selects Left channel ADC output.
0 = ADC Left channel
1 = ADC Right channel
5
AIFADCR_SRC
1
Selects Right channel ADC output.
0 = ADC Left channel
1 = ADC Right channel
4
AIFADC_TDM_
CHAN
0
ADCDAT TDM Channel Select
0 = ADCDAT outputs data on slot 0
1 = ADCDAT output data on slot 1
3
AIFADC_TDM
0
ADC TDM Enable
0 = Normal ADCDAT operation
1 = TDM enabled on ADCDAT
7
AIFDAC_PD
0
Enables a pull down on DAC data pin
0 = disabled
1 = enabled
6
DACL_SRC
0
Selects Left channel DAC input.
0 = DAC Left channel
1 = DAC Right channel
5
DACR_SRC
1
Selects Right channel DAC input.
0 = DAC Left channel
1 = DAC Right channel
4
AIFDAC_TDM_
CHAN
0
DACDAT TDM Channel Select
0 = DACDAT outputs data on slot 0
1 = DACDAT output data on slot 1
3
AIFDAC_TDM
0
DAC TDM Enable
0 = Normal DACDAT operation
1 = TDM enabled on DACDAT
Table 46 Selecting the Audio Data Format
In Left Justified mode, the MSB is available on the first rising edge of BCLK following an LRCLK
transition. The other bits up to the LSB are then transmitted in order. Depending on word length,
BCLK frequency and sample rate, there may be unused BCLK cycles before each LRCLK transition.
1/fs
LEFT CHANNEL
RIGHT CHANNEL
LRCLK
BCLK
DACDAT/
ADCDAT
1
MSB
2
3
n-2
Input Word Length (WL)
n-1
n
1
2
3
n-2
n-1
n
LSB
Figure 50 Left Justified Audio Interface (assuming n-bit word length)
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In Right Justified mode, the LSB is available on the last rising edge of BCLK before a LRCLK
transition. All other bits are transmitted before (MSB first). Depending on word length, BCLK
frequency and sample rate, there may be unused BCLK cycles after each LRCLK transition.
Figure 51 Right Justified Audio Interface (assuming n-bit word length)
In I2S mode, the MSB is available on the second rising edge of BCLK following a LRCLK transition.
The other bits up to the LSB are then transmitted in order. Depending on word length, BCLK
frequency and sample rate, there may be unused BCLK cycles between the LSB of one sample and
the MSB of the next.
Figure 52 I2S Audio Interface (assuming n-bit word length)
In DSP/PCM mode, the left channel MSB is available on either the 1st (mode B) or 2nd (mode A)
rising edge of BCLK (selectable by AIF_LRCLK_INV) following a rising edge of LRCLK. Right
channel data immediately follows left channel data. Depending on word length, BCLK frequency and
sample rate, there may be unused BCLK cycles between the LSB of the right channel data and the
next sample.
Figure 53 DSP/PCM Mode Audio Interface (mode A, AIF_LRCLK_INV=0)
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Figure 54 DSP/PCM Mode Audio Interface (mode B, AIF_LRCLK_INV=1)
13.10.2 AUDIO INTERFACE TDM MODE
The digital audio interface on WM8351 has the facility of tri-stating the ADCDAT pin to allow multiple
data sources to operate on the same bus. Time division multiplexing (TDM) is also supported,
allowing audio output data to be transferred simultaneously from two different sources.
TDM mode is enabled for the ADC and DAC by register bits AIFADC_TDM and AIFDAC_TDM
respectively. TDM slot selection for the WM8351 is set for the ADC and DAC by register bits
AIFADC_TDM_CHAN and AIFDAC_TDM_CHAN respectively, as defined in Table 46. When not
actively transmitting data, the ADCDAT pin will be tristated in TDM mode, to allow other devices to
transmit data.
13.10.3 TDM DATA FORMATS
All selectable data formats support TDM. The allocation of time slots is controlled by register bits
AIFADC_TDM_CHAN and AIFDAC_TDM_CHAN. Two possible slots (SLOT0 and SLOT1) are
available for the ADC and for the DAC.
Timing signals for the various interface formats in TDM mode are shown below for the ADC. Similar
slot allocation will exist for the DAC.
Left Justified Mode: SLOT0 and SLOT1 are defined as shown below. The number of BCLK cycles
from the start of SLOT0 to the start of SLOT1 is determined by the selected word length of the
interface of the WM8351.
Figure 55 Left Justified Mode with TDM
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Right Justified Mode: SLOT0 and SLOT1 are defined as shown below. The number of BCLK cycles
from the end of SLOT1 to the end of SLOT0 is determined by the selected word length of the
interface of the WM8351.
Figure 56 Right Justified Mode with TDM
I2S Mode: SLOT0 and SLOT1 are defined as shown below. The number of BCLK cycles from the
start of SLOT0 to the start of SLOT1 is determined by the selected word length of the interface of the
WM8351.
Figure 57 I2S Mode with TDM
DSP/PCM Mode A, Master Mode: SLOT0 and SLOT1 are defined as shown below. The number of
BCLK cycles from the start of SLOT0 (left) to the start of SLOT1 (left) is determined by the selected
word length of the interface of the WM8351.
Figure 58 DSP/PCM Mode A, Master Mode with TDM
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DSP/PCM Mode B, Master Mode: SLOT0 and SLOT1 are defined as shown below. The number of
BCLK cycles from the start of SLOT0 (left) to the start of SLOT1 (left) is determined by the selected
word length of the interface of the WM8351.
Figure 59 DSP/PCM Mode B, Master Mode, with TDM
DSP/PCM Mode A, Slave Mode: SLOT0 and SLOT1 are defined as shown below. The number of
BCLK cycles from the start of SLOT0 (left) to the start of SLOT1 (left) is determined by the selected
word length of the interface of the WM8351.
Figure 60 DSP/PCM Mode A, Slave Mode with TDM
DSP/PCM Mode B, Slave Mode: SLOT0 and SLOT1 are defined as shown below. The number of
BCLK cycles from the start of SLOT0 (left) to the start of SLOT1 (left) is determined by the selected
word length of the interface of the WM8351.
Figure 61 DSP/PCM Mode B, Slave Mode, with TDM
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13.10.4 LOOPBACK
When the loopback feature is enabled, the audio ADC’s digital output data is looped back to the
audio DAC and converted back into an analogue signal. This is often useful for test and evaluation
purposes.
ADDRESS
R113 (71h)
ADC Control
BIT
LABEL
DEFAULT
0
LOOPBACK
0
DESCRIPTION
Digital Loopback Function
0 = No loopback.
1 = Loopback enabled, ADC data output is
fed directly into DAC data input.
Table 47 Enabling loopback
13.11 COMPANDING
The WM8351 supports A-law and μ-law companding on both transmit (ADC) and receive (DAC)
sides. Companding can be enabled on the DAC or ADC audio interfaces by writing the appropriate
value to the DAC_COMP or ADC_COMP register bits respectively.
REGISTER
ADDRESS
R113 (71h)
Companding
Control
BIT
LABEL
DEFAULT
DESCRIPTION
4
ADC_COMPM
ODE
0
ADC Companding mode select:
0 = μ-law
1 = A-law
(Note: Setting ADC_COMPMODE=1
selects 8-bit mode when DAC_COMP=0
and ADC_COMP=0)
5
ADC_COMP
0
ADC Companding enable
0 = off
1 = on
6
DAC_COMPM
ODE
0
DAC Companding mode select:
0 = μ-law
1 = A-law
(Note: Setting DAC_COMPMODE=1
selects 8-bit mode when DAC_COMP=0
and ADC_COMP=0)
7
DAC_COMP
0
DAC Companding enable
0 = off
1 = on
Table 49 Companding Control
Companding involves using a piecewise linear approximation of the following equations (as set out
by ITU-T G.711 standard) for data compression:
μ-law (where μ=255 for the U.S. and Japan):
F(x) = ln( 1 + μ|x|) / ln( 1 + μ)
-1 ≤ x ≤ 1
law (where A=87.6 for Europe):
F(x) = A|x| / ( 1 + lnA)
} for x ≤ 1/A
F(x) = ( 1 + lnA|x|) / (1 + lnA)
} for 1/A ≤ x ≤ 1
The companded data is also inverted as recommended by the G.711 standard (all 8 bits are inverted
for μ-law, all even data bits are inverted for A-law). The data will be transmitted as the first 8 MSBs
of data.
Companding converts 13 bits (μ-law) or 12 bits (A-law) to 8 bits using non-linear quantization. This
provides greater precision for low amplitude signals than for high amplitude signals, resulting in a
greater usable dynamic range than 8 bit linear quantization. The companded signal is an 8-bit word
comprising sign (1 bit), exponent (3 bits) and mantissa (4-bits).
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8-bit mode is selected whenever DAC_COMP=1 or ADC_COMP=1. The use of 8-bit data allows
samples to be passed using as few as 8 BCLK cycles per LRCLK frame. When using DSP mode B,
8-bit data words may be transferred consecutively every 8 BCLK cycles.
8-bit mode (without Companding) may be enabled by setting ADC_COMPMODE=1 when
ADC_COMP=0.
BIT7
BIT[6:4]
BIT[3:0]
SIG
N
EXPONENT
MANTISSA
Table 50 8-bit Companded Word Composition
u-law Companding
1
120
0.9
Companded Output
0.7
80
0.6
0.5
60
0.4
40
0.3
Normalised Output
0.8
100
0.2
20
0.1
0
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Normalised Input
Figure 39 μ-Law Companding
A-law Companding
1
120
0.9
Companded Output
0.7
80
0.6
0.5
60
0.4
40
0.3
Normalised Output
0.8
100
0.2
20
0.1
0
0
0
0.2
0.4
0.6
0.8
1
Normalised Input
Figure 40 A-Law Companding
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13.12 ADDITIONAL CODEC FUNCTIONS
13.12.1 HEADPHONE JACK DETECT
The IN2L and IN2R pins can be selected as headphone jack detect inputs, to enable automatic
control of the analogue outputs when a headphone is plugged into a jack socket.
Jack Detection on the IN2L or IN2R pins is enabled by register bits JDL_ENA or JDR_ENA
respectively. When Jack Detection is enabled, the associated second level interrupts
CODEC_JCK_DET_L_EINT and CODEC_JCK_DET_R_EINT indicate the status of the jack socket.
See Section 13.12.7 for further details.
The Headphone Jack Detect function requires the internal slow clock to be enabled - see
Section 12.3.6.
REGISTER
ADDRESS
R77 (4Dh)
Jack Detect
BIT
LABEL
DEFAULT
DESCRIPTION
15
JDL_ENA
0
Jack Detect Enable for inputs connected
to IN2L
0 = disabled
1 = enabled
14
JDR_ENA
0
Jack Detect Enable for input connected
to IN2R
0 = disabled
1 = enabled
Table 48 Headphone Jack Detect
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13.12.2 MICROPHONE DETECTION
The WM8351 can detect when a microphone has been plugged in, and/or when the microphone is
short-circuited. It detects these events by comparing the current drawn from the MICBIAS pin against
two thresholds. The thresholds for plug-in detection and short-circuit detection are programmable.
A MICBIAS current above the MCDTHR threshold level is used to indicate that a microphone is
plugged in, and is associated with the CODEC_MICD_EINT interrupt. If the bias current exceeds the
MCDSCTHR limit, this indicates a microphone short-circuit condition, and the WM8351 raises a
CODEC_MICSCD_EINT interrupt. See Section 13.12.7 for further details. Note that the MICBIAS
current thresholds are subject to a wide tolerance - up to +/-50% of the specified value.
Microphone detection requires the internal slow clock to be enabled - see Section 12.3.6.
ADDRESS
R8 (08h)
Power Mgmt 1
R74 (4Ah)
Mic Bias
Control
BIT
LABEL
DEFAULT
8
MIC_DET_ENA
0
DESCRIPTION
Enable MIC detect:
0 = disabled
1 = enabled
7
MIC_DET_ENA
0
4:2
MCDTHR [2:0]
000
Threshold for bias current detection
000 = 160μA
001 = 330μA
010 = 500μA
011 = 680μA
100 = 850μA
101 = 1000μA
110 = 1200μA
111 = 1400μA
These threshold currents scale
proportionally with AVDD. The values
given are for AVDD=3.3V.
1:0
MCDSCTHR
[1:0]
00
Threshold for microphone short-circuit
detection
00 = 400μA
01 = 900μA
10 = 1350μA
11 = 1800μA
These threshold currents scale
proportionally with AVDD. The values
given are for AVDD=3.3V.
Note: MIC_DET_ENA can be accessed through R8 or through R74. Reading from or writing to either
register location has the same effect.
Table 49 Controlling Microphone Bias Current Detection
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13.12.3 MID-RAIL REFERENCE (VMID)
VMID provides a potential mid-way between AVDD and GND, used in many parts of the audio
CODEC. It is generated from AVDD using on-chip potential dividers. Different resistor values can be
selected for this purpose. A medium resistance should be used when the CODEC is active. A high
resistance option provides a more power-efficient way to maintain the VMID voltage when the
CODEC is in “Standby” (i.e. inactive but ready to start immediately, without needing to wait for the
VMID capacitor to be charged). For startup and shutdown the VMID generator provides soft VMID
ramping to reduce pops and clicks. The speed of this ramp is selectable using the anti-pop controls
and can be tuned to the application.
Figure 62 Generating the Mid-rail Reference
ADDRESS
BIT
R8 (08h)
Power
Management 1
2
VMID_EN
A
LABEL
DEFAULT
0
1:0
VMID [1:0]
00
(off)
DESCRIPTION
Enables VMID resistor string
0 = disabled, 1 = enabled
Resistor selection for VMID potential divider
00 = off
01 = VMID comes from 300kΩ R-string
10 = VMID comes from 50kΩ R-string
11 = VMID comes from 5kΩ R-string
Table 50 Controlling the Mid-rail Reference
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13.12.4 ANTI-POP CONTROL
ADDRESS
R78 (4Eh)
Anti pop
control
DEFAULT
DESCRIPTION
9:8
BIT
ANTI_POP [1:0]
LABEL
00
Reduces pop when VMID is enabled by setting
the speed of the S-ramp for VMID.
00 = no S-ramp (will pop)
01 = fastest S-curve
10 = medium S-curve
11 = slowest S-curve
7:6
DIS_OP_LN4 [1:0]
00
Sets the Discharge rate for OUT4
00 = discharge path OFF
01 = fastest discharge
10 = medium discharge
11 = slowest discharge
5:4
DIS_OP_LN3 [1:0]
00
Sets the Discharge rate for OUT3
00 = discharge path OFF
01 = fastest discharge
10 = medium discharge
11 = slowest discharge
3:2
DIS_OP_OUT2 [1:0]
00
Sets the discharge rate for OUT2L and OUT2R
00 = discharge path OFF
01 = fastest discharge
10 = medium discharge
11 = slowest discharge
1:0
DIS_OP_OUT1 [1:0]
00
Sets the discharge rate for OUT1L and OUT1R
00 = discharge path OFF
01 = fastest discharge
10 = medium discharge
11 = slowest discharge
Table 51 Control Registers for Anti-pop
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13.12.5 UNUSED ANALOGUE INPUTS/OUTPUTS
Whenever an analogue input/output is disabled, it remains connected to AVDD/2 through a resistor.
This helps to prevent pop noise when the output is re-enabled. The resistance between the voltage
buffer and the output pins can be controlled using the VROI control bits. The default impedance is
low, so that any capacitors on the outputs can charge up quickly at start-up. If high impedance is
desired for disabled outputs, VROI can then be set to 1, increasing the resistance to about 30kΩ.
There are individual VROI bits for each output or output pair. This allows matching of the rise times
of the outputs if they are driving different capacitors. Using the small resistance with a capacitor for
headphone outputs (typically 220uF) and the larger resistance with a line load capacitance (10uF for
example); will allow both sets of outputs to power up in around the same time, around 200ms.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R8 (08h)
Power Mgmt
1
13
VBUF_ENA
0
Forces ON the tie-off amplifiers
0 = Disabled
1 = Enabled
R76 (4Ch)
Output
Control
8
OUT1_VROI
0
VREF (AVDD/2) to OUT1L/OUT1R
resistance
0 = approx 500Ω
1 = approx 30 kΩ
9
OUT2_VROI
0
VREF (AVDD/2) to OUT2L/OUT2R
resistance
0 = approx 500Ω
1 = approx 30 kΩ
10
OUT3_VROI
0
VREF (AVDD/2) to OUT3 resistance
0 = approx 500Ω
1 = approx 30 kΩ
11
OUT4_VROI
0
VREF (AVDD/2) to OUT4 resistance
0 = approx 500Ω
1 = approx 30 kΩ
Table 52 Disabled Outputs to VREF Resistance
A dedicated buffer is available for tying off unused analogue I/O pins as shown below. This buffer
can be enabled using the VBUF_ENA register bit.
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AVDD/2
+
AVDD/2
500
VBUF_ENA
R8[13]
Used to tie off all unused
inputs.
OUT1L
30k
OUT1L_ENA OUT1_VROI
R76[8]
R10[0]
500
OUT1R
30k
AVDD/2
+
AVDD/2
OUT1R_ENA
R10[1]
500
OUT4
VBUF_ENA
R8[13]
Used to tie off all unused
outputs.
30k
OUT4_ENA
R9[5]
OUT4_VROI
R76[11]
500
OUT3
30k
OUT3_VROI
R76[10]
OUT3_ENA
R9[4]
500
OUT2L
30k
OUT2L_ENA OUT2_VROI
R76[9]
R10[2]
500
OUT2R
30k
OUT2R_ENA
R10[3]
Figure 63 Unused Input/Output Pin Tie-off Buffers
OUT1R/L_ENA/
OUT2R/L_ENA
OUT3/4_ENA
VROI
OUTPUT CONFIGURATION
0
0
500Ω tie-off to AVDD/2
0
1
30kΩ tie-off to AVDD/2
1
X
Output enabled (DC level = AVDD/2)
1
X
Output enabled (DC level = 1.5 x AVDD/2)
Table 53 Unused Output Pin Tie-off Options
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13.12.6 ZERO CROSS TIMEOUT
A zero-cross timeout function is also provided so that if zero cross is enabled on the input or output
PGAs the gain will automatically update after a timeout period if a zero cross has not occurred.
The zero-cross timeout function requires the internal slow clock to be enabled - see Section 12.3.6.
13.12.7 INTERRUPTS AND FAULT PROTECTION
The CODEC has its own first-level interrupt, CODEC_INT (see Section 24). This comprises four
second-level interrupts which indicate Jack detect and Microphone current conditions. These
interrupts can be individually masked by setting the applicable mask bit(s) as described in Table 54.
ADDRESS
R31 (1Fh)
Comparator
Interrupt
Status
R39 (27h)
Comparator
Interrupt
Status Mask
BIT
LABEL
DESCRIPTION
11
CODEC_JCK_DET_L_EINT
Left channel Jack detection interrupt.
(Rising and Falling Edge triggered)
Note: This bit is cleared once read.
10
CODEC_JCK_DET_R_EINT
Right channel Jack detection interrupt.
(Rising and Falling Edge triggered)
Note: This bit is cleared once read.
9
CODEC_MICSCD_EINT
Mic short-circuit detect interrupt.
(Rising and Falling Edge triggered)
Note: This bit is cleared once read.
8
CODEC_MICD_EINT
Mic detect interrupt.
(Rising and Falling Edge triggered)
Note: This bit is cleared once read.
“IM_” + name of respective
bit in R31
Interrupt mask.
0 = Do not mask interrupt.
1 = Mask interrupt.
Each bit in R39 enables or masks the
corresponding bit in R31. The default
value for these bits is 0 (unmasked).
11:8
Table 54 CODEC Interrupts
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14 POWER MANAGEMENT SUBSYSTEM
14.1 GENERAL DESCRIPTION
The WM8351 provides five DC-DC Converters and four LDO Regulators which each deliver high
efficiency across a wide range of line and load conditions. These power management components
are designed to support application processors and associated peripherals. They are also suitable for
providing power to the analogue and digital functions of the on-board CODEC and GPIO features.
The output voltage of each of the converters and regulators is programmable in software through
control registers.
The WM8351 has a number of operating states which are either selected by software control or are
selected autonomously according to the available power supply conditions. A low power active
‘Hibernate’ state is provided, with programmable characteristics. The ‘Backup’ and ‘Zero’ states are
selected autonomously when the available supply voltages do not permit full operation of the
WM8351.
Four configuration modes are provided, selected by hardware control. Development Mode gives
complete control over the configuration and start-up behaviour of the WM8351. Three different
Custom Modes each have a defined set of configuration parameters, which determine the start-up
timing and output voltage of each of the DC-DC Converters and LDO Regulators. The configuration
of each of the GPIO pins is also contained with the configuration modes definitions.
14.2 POWER MANAGEMENT OPERATING STATES
The WM8351 autonomously controls the power-up and power-down sequencing for itself and for
other connected devices. It also selects the most appropriate power source available at any given
time (see Section 17). The stable states of the WM8351 are:
ACTIVE - All WM8351 functions can be used. The WM8351 enters the ACTIVE state after a valid
start-up event (see Section 14.3.1), provided that no fault condition occurred during start-up.
HIBERNATE - This is an alternative active state with programmable characteristics, allowing an
optional low power system condition. The internally generated supply voltages can be individually
enabled or disabled as desired. The WM8351 enters the HIBERNATE state from ACTIVE by setting
the HIBERNATE register bit or when commanded via a GPIO pin configured as a HIBERNATE
alternate function.
OFF - All DC-DC converters and regulators LDO2, LDO3 and LDO4 are disabled. LDO1 may remain
active (See Section 14.7.4). The VRTC regulator remains active and powers the always-on functions
(such as crystal oscillator and RTC.) Register settings are restored to default settings. Trickle
charging for the main battery is enabled by default. The WM8351 enters the OFF state from ACTIVE
if a shutdown event occurs (see Section 14.3.3), or if the power source falls below the shutdown
threshold (see Section 18). The WM8351 enters the OFF state from BACKUP if a power source
greater than the UVLO threshold becomes available.
BACKUP - The crystal oscillator and RTC are enabled, powered from the backup power (VRTC)
supply. All other functions are disabled. The WM8351 enters the BACKUP state from OFF if the
power source falls below the UVLO threshold (see Section 18), and provided that backup power
(VRTC) is available (i.e. LINE falls below the UVLO level but VRTC remains above the Power-On
Reset threshold).
ZERO - All functions are disabled and all data in registers is lost. The WM8351 goes into this state
when no power source is available and VRTC falls below the Power-On Reset threshold.
The Active state can only be entered via the PRE-ACTIVE state. In Development Mode, the PreActive state is the state in which the WM8351 start-up parameters may be defined, prior to the startup sequence being triggered. The ACTIVE state is only entered on completion of the start-up
sequence.
The WM8351 operating states and valid transitions are illustrated in Figure 64.
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Figure 64 WM8351 Operating State Diagram
14.2.1
HIBERNATE STATE SELECTION
The WM8351 moves from the ACTIVE to the HIBERNATE state when the HIBERNATE register bit is
set. It can also move to hibernate using the Hibernate Edge or the Hibernate Level function from the
GPIOs.
It returns to the ACTIVE state when the Hibernate Level GPIO function is reset and the HIBERNATE
bit is set to 0. It can also return to ACTIVE via the Hibernate Edge function or when a wake-up event
(see Section 14.3.1) occurs.
If a fault condition occurs in the HIBERNATE state, the WM8351 moves to the OFF state.
ADDRESS
BIT
LABEL
DEFAULT
R5 (05h)
System
Hibernate
15
HIBERNATE
0
DESCRIPTION
Determines what state the chip should
operate in.
0 = Active state
1 = Hibernate state
The register bit defaults to 0 when a reset
happens
Table 55 Invoking HIBERNATE State
The behaviour of the WM8351 in the HIBERNATE state is programmable in terms of supply voltage
generation, interrupts and resets. Fast battery charging is disabled in the HIBERNATE state, but
trickle charging is possible.
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14.3 POWER SEQUENCING AND CONTROL
14.3.1
STARTUP
The WM8351 moves from OFF or HIBERNATE states to the ACTIVE state when a startup event
occurs. Startup events include:
•
A trigger signal on the ON pin lasting more than 40ms. The active polarity of this input is set by
the register field ON_POL.
•
A trigger signal on a GPIO pin configured as /WAKEUP lasting more than 40ms. The active
polarity of this input is set by GPn_CFG for the applicable GPIO pin (see Section 20).
•
A trigger signal on a GPIO pin configured as PWR_ON input lasting more than 40ms. The
active polarity of this input is set by GPn_CFG for the applicable GPIO pin (see Section 20).
•
Programmed ALARM from RTC module, if enabled (see Section 22).
•
Wall adaptor plug-in (WALL_FB rises above 4.0V).
•
USB plug-in (USB pin rises above 4.0V).
The start-up events are only valid provided also that the available supply voltage, sensed on the
LINE pin, is greater than the start-up threshold set by PCCMP_ON_THR, as defined in Section 18.
Start-Up by Wall adaptor plug-in occurs when the Wall Adapter feedback pin detects a voltage
greater than 4.0V. See Section 17.1 for a description of the WALL_FB pin function.
Start-Up by USB plug-in occurs when the USB voltage rises above the LINE voltage. If USB
Suspend mode is invoked, then USB plug-in starts the WM8351 on battery power, if available. When
USB Suspend Mode is not invoked, this start-up event will lead to starting the WM8351 on USB
power, and USB 100mA trickle charging of the battery is enabled.
Note that applying a battery voltage is not a start-up event, i.e. connecting a battery pack does not
start the WM8351. The WM8351 starts up on battery power if a startup event occurs and battery
power is the only power source available, provided the battery voltage is above the startup threshold.
(The start-up threshold is set by PCCMP_ON_THR, as defined in Section 18.)
In the ACTIVE state, the host processor can read the Interrupt status fields in Register R31 in order
to determine what action initiated the start-up. These fields indicate, for example, if the start-up was
due to a reset caused by an error condition, or if the start-up was caused by a PWR_ON input, or if
the start-up was caused by an RTC alarm. The first-level interrupt WKUP_INT is triggered whenever
any of the second-level interrupt events described in Table 56 is set. See Section 24 for further
details of Interrupt.
ADDRESS
R31 (1Fh)
Comparator
Interrupt
Status
w
BIT
LABEL
DESCRIPTION
6
WKUP_OFF_STATE_EINT
Indicates that the chip started from the
OFF state.
(Rising Edge triggered)
Note: This bit is cleared once read.
5
WKUP_HIB_STATE_EINT
Indicated the chip started up from the
hibernate state.
(Rising Edge triggered)
Note: This bit is cleared once read.
4
WKUP_CONV_FAULT_EINT
Indicates the wakeup was caused by a
converter fault leading to the chip being
reset.
(Rising Edge triggered)
Note: This bit is cleared once read.
3
WKUP_WDOG_RST_EINT
Indicates the wakeup was caused by a
watchdog heartbeat being missed, and
hence the chip being reset.
(Rising Edge triggered)
Note: This bit is cleared once read.
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ADDRESS
R39 (27h)
Comparator
Interrupt
Status Mask
BIT
LABEL
2
WKUP_GP_PWR_ON_EINT
PWR_ON (Alternate GPIO function) pin
has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
1
WKUP_ONKEY_EINT
ON key has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
0
WKUP_GP_WAKEUP_EINT
WAKEUP (Alternate GPIO function) pin
has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
“IM_” + name of respective
bit in R31
Interrupt mask.
0 = Do not mask interrupt.
1 = Mask interrupt.
Each bit in R39 enables or masks the
corresponding bit in R31. The default
value for these bits is 0 (unmasked).
6:0
DESCRIPTION
Table 56 Wake-Up Interrupts
14.3.2
POWER-UP SEQUENCING
The WM8351 power supply blocks can be commanded to start up according to a defined sequence
when the WM8351 is commanded into the ACTIVE state. This sequence comprises fourteen
timeslots, where the enabling of each DC-DC converter, LDO voltage regulator and the current limit
switch is associated with one timeslot. In order to minimise supply in-rush current at power-up time,
the start-up of these power supply blocks should be staggered in time by the use of this feature.
The WM8351 proceeds from one time slot to the next after a delay of approximately 1.28ms,
provided that all power supply blocks started up in the current time slot (if any) have reached 90% of
their programmed output voltage. See Section 14.3.4 for details of the WM8351 behaviour if any
power supply block fails to achieve 90% of its programmed output voltage.
14.3.3
SHUTDOWN
The WM8351 goes from ACTIVE or HIBERNATE to the OFF state when a shutdown event occurs.
Shutdown events include:
•
Software shutdown (setting CHIP_ON = 0)
•
A trigger signal on a GPIO pin configured as PWR_OFF lasting more than 5ms. The active
polarity of this input is set by GPn_CFG for the applicable GPIO pin (see Section 20).
•
A trigger signal on the ON pin lasting more than 10 seconds. The active polarity of this input is
set by the register field ON_POL. If required, the de-bounce time can be set to 5 seconds using
the ON_DEB_T register bit.
•
Watchdog time-out (see Section 23) after 7 previous faults.
•
Fault conditions programmed to trigger a shutdown (see Section 18).
•
Thermal shutdown (see Section 25)
As part of the start-up sequence, the CHIP_ON bit is set to 1. The software shutdown is commanded
by writing 0 to the CHIP_ON register field as described in Table 57.
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ADDRESS
BIT
R3 (03h)
System
Control 1
15
CHIP_ON
LABEL
DEFAULT
0
Indicates whether the system is on or off.
Writing 0 to this bit powers down the whole
chip. Registers which are affected by state
machine reset will get reset.
Once the system is turned OFF it can be
restarted by any of the valid ON event.
DESCRIPTION
3
ON_DEB_T
0
ON pin off function debounce time
0 = 10s
1 = 5s
1
ON_POL
1
ON pin polarity:
0 = Active high (ON)
1 = Active low (/ON)
Table 57 Software Shutdown
As part of the shutdown sequence, the WM8351 asserts the /RST and /MEMRST reset signals,
resets its internal control registers, disables most of its functions, resets the CHIP_ON bit to 0 and
moves to the OFF state. (Note that /MEMRST is an optional output available on GPIO pins only.)
14.3.4
POWER CYCLING
If an undervoltage fault or a limit switch overcurrent fault is detected (eg. during start-up, or when
exiting the HIBERNATE state), the WM8351 will respond according to various configurable options.
The Limit Switch and each of the DC Converters and LDO Regulators may be programmed to
shutdown the system in the event of a fault condition. In these events (where a system shutdown is
selected), the WM8351 will either shut down or will attempt to re-start, depending on the state of the
POWERCYCLE register bit.
If POWERCYCLE = 0, then a fault condition will result in the shutdown of the WM8351, reverting to
the OFF state. If POWERCYCLE = 1, then the WM8351 will make a maximum of 8 attempts to restart. Each attempt will be scheduled at 200ms intervals. After 8 consecutive failed attempts, the
WM8351 reverts to the OFF state and resets the power cycling counter. Any subsequent start-up
event again has a maximum of 8 attempts to start up (provided that POWERCYCLE = 1).
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R3 (03h)
System
Control
13
POWERCYCL
E
0
Action to take on a fault (if fault response
is set to shutdown system):
0 = Shut down
1 = Shutdown everything then go through
startup sequence. ie. Reboot the system.
Table 58 Controlling Power Cycling
14.3.5
REGISTER RESET
The control registers of the WM8351 are reset when it goes into the OFF state. Under default
conditions, the control registers are also reset when exiting the HIBERNATE state; this behaviour is
selectable using the REG_RESET_HIB_MODE control bit.
In Development mode, the register reset in OFF can be disabled using the RECONFIG_AT_ON
register field. See Section 14.4 for a definition of this field.
ADDRESS
R5 (05h)
System
Hibernate
BIT
LABEL
DEFAULT
5
REG_RESE
T_HIB_MOD
E
0
DESCRIPTION
Action of the internal register reset signal
when going from Hibernate to Active.
0 = Do a register reset when leaving the
hibernate state.
1 = Do not do a register reset when leaving
the hibernate state
Table 59 Register Reset Control
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14.3.6
RESET SIGNALS
The WM8351 provides an active-low reset output signal to the host processor on the open-drain
/RST pin. The /RST pin is asserted low in the OFF state. The status of the /RST pin in HIBERNATE
state is configurable using the RST_HIB_MODE bit.
In start-up, after all enabled power supplies reach 90% of their programmed output voltage, the /RST
output is held low for a programmable duration set by RSTB_TO. The /RST pin is then set high. The
/RST output is set low during the shutdown sequence.
In Configuration Mode 11 only, the “crystal detect” mode is enabled; this controls the /RST output
behaviour. In this mode, the WM8351 monitors the 32kHz crystal oscillator during start-up to verify
that the output frequency is valid. The /RST output is held low until this has been achieved.
An additional GPIO output, /RST can be generated, with the same functionality as the /RST pin. A
GPIO pin must be configured as /RST in order to output this signal (see Section 20).
The WM8351 can also generate a separate /MEMRST signal for other subsystems such as external
memory. This allows resetting some subsystems in the HIBERNATE state, while not resetting others.
The /MEMRST feature is provided via a GPIO pin (see Section 20). Note that /MEMRST is not a
valid control signal during the start-up as the GPIO pins are not configured at this time. The
MEM_VALID field provides an indication of whether the contents of the external memory (under
control of /MEMRST) are valid.
The /RST and /MEMRST signals can also be asserted under control of a manual reset input. A GPIO
pin (see Section 20) must be configured as /MR to enable this feature. Note that the /MR input has
no effect on the WM8351 circuits other than asserting /RST and /MEMRST.
ADDRESS
R3 (03h)
System
Control 1
R5 (05h)
System
Hibernate
BIT
LABEL
DEFAULT
DESCRIPTION
11:10
RSTB_TO
[1:0]
11
Time that the /RST pin and /MEMRST
output is held low after the chip reaches the
active state.
00 = 15ms
01 = 30ms
10 = 60ms
11 = 120ms
5
MEM_VALID
0
Indicates that the contents of external
memory are still valid.
This bit is cleared on startup and whenever
/MEMRST is asserted from the main state
machine. The system software should set
this bit once the external memory has been
set up.
Controlled in hibernate mode by
MEMRST_HIB_MODE
0 = External memory is not valid and needs
restoring.
1 = External memory is valid.
4
RST_HIB_M
ODE
0
/RST pin state in hibernate mode:
0 = Asserted (low)
1 = Not asserted (high)
2
MEMRST_H
IB_MODE
0
/MEMRST (Alternative GPIO function) pin
state in hibernate mode
0 = Asserted (low)
1 = Not asserted (high)
Table 60 Controlling Reset Signals
The WM8351 can be commanded to assert the /RST and /MEMRST signals by writing a logic ‘1’ to
the SYS_RST register bit. In this case, the /RST and /MEMRST outputs are asserted low for the
duration specified by RSTB_TO.
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Care must be taken if writing to this bit in 2-wire (I2C) Control Interface mode. The WM8351 will act
upon the register write operation as soon as it has received the address and data fields; this may
happen before the I2C Acknowledge has been clocked by the host processor. If the /RST signal
causes the processor to reset before it has clocked the I2C Acknowledge, then the WM8351 will
continue to assert the Acknowledge signal (ie. pull the SDA pin low) after the processor has
completed its reset. On some processors, it may be necessary to toggle the SCLK pin in order to
clear the Acknowledge signal and resume I2C communications.
ADDRESS
BIT
R3 (03h)
System
Control 1
14
LABEL
SYS_RST
DEFAULT
DESCRIPTION
0
Allows the processors to reboot itself
0 = Do nothing
1 = Perform a processor reset by asserting
the /RST and /MEMRST (GPIO) pins for the
programmed duration
Protected by security key.
Table 61 Software Reset Command
14.4 DEVELOPMENT MODE
The WM8351 can start in different modes depending on the state of the CONF1 and CONF0 pins.
Development mode is selected by tying CONF1 and CONF0 to logic 0.
Development mode gives complete control over the configuration and startup behaviour of the
WM8351 and allows overriding the default values of selected registers (listed in Table 64). It enables
configuration of the WM8351 before startup. This is especially useful for evaluation and debugging.
In low-volume production, an external ‘genie’ (low-cost, small-size microcontroller) may be used to
configure the WM8351 in Development mode. The ‘genie’ is used to write the required register
values to generate the desired supplies and to configure the GPIO pins as required. These register
write operations can be achieved via a secondary control interface, which is provided by redirecting
the control interface to two GPIO pins as described below.
The configuration mode pins CONF1 and CONF0 should be tied to fixed logic levels. The start-up
sequence that they control is initiated on every transition from the OFF to the ACTIVE state.
14.4.1
CONTROL INTERFACE REDIRECTION
In Development mode, the 2-wire control interface is initially redirected from the primary control
interface (dedicated SDATA and SCLK pins, which require a DBVDD supply) to the secondary
control interface (the GPIO10 and GPIO11 pins, which can run on an externally generated supply
provided through the LINE pin). When using GPIO pins for the Control Interface, GPIO11 provides
the SDATA functionality, and GPIO10 provides the SCLK functionality.
Use of the secondary interface makes it possible to configure the WM8351 before the DBVDD supply
voltage becomes available (e.g. in the OFF and PRE-ACTIVE states). The control interface can be
switched back to the primary interface at any time by writing to the USE_DEV_PINS bit. In a typical
application, the primary control interface would be selected after the WM8351 is fully configured.
The device address for the secondary control interface is 0x34h, and cannot be changed. In
development mode only, the primary interface address can be selected by writing to the DEV_ADDR
bits through the secondary interface. Note that this functionality is only available in Development
mode.
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ADDRESS
R6 (06h)
Interface
Control
BIT
LABEL
DEFAULT
DESCRIPTION
15
USE_DEV_
PINS
1
Selects which pins to use for the 2-wire
control:
0 = Use 2-wire I/F pins as 2-wire interface
1 = Use GPIO 10 and 11 as 2-wire interface,
e.g. to download settings from PIC.
Only applies when CONFIG pins[1:0] = 00.
14:13
DEV_ADDR
[1:0]
00
Selects device address (only valid when
CONF_STS = 00)
00 = 0x34
01 = 0x36
10 = 0x3C
11 = 0x3E
Note: In custom modes (CONF[1:0]≠00), the secondary control interface is never used and the
control bits described here have no effect.
Table 62 Control Interface Switching in Development Mode
14.4.2
STARTING UP IN DEVELOPMENT MODE
In Development mode, the GPIO1 pin is configured as a DO_CONF output (see Section 20), which is
asserted high to indicate that the WM8351 is about to start up. This may be used to trigger the
‘genie’ to configure the WM8351 via the secondary control interface.
Figure 65 Configuration Timing in Development Mode
On completion of the register configuration, the power-up sequence is initiated by writing a logic 1 to
the CONFIG_DONE bit. If the CONFIG_DONE bit is not set before the maximum set-up time has
elapsed (see Figure 65), then the WM8351 will revert to the OFF state.
An alternative implementation is to start up the WM8351 by setting CONFIG_DONE to ‘1’ without
first programming the converter/LDO settings. By this method, the rising edge of the /RST signal may
be used to trigger the WM8351 configuration process after the device has entered the ACTIVE state.
In this case, the DC-DC converters and LDOs turn on immediately when they are enabled (time slots
are no longer relevant because the WM8351 is already in the ACTIVE state). To reduce in-rush
current, any configuration sequence triggered by /RST should therefore include supply staggering in
software (i.e. time delays between powering up individual supply domains).
Note that, whether using DO_CONF or /RST to trigger configuration, the on-chip watchdog imposes
a time-out for configuration; if the WM8351 watchdog is not serviced, it restarts the system. This can
be prevented, if necessary, by disabling the watchdog.
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By default, the DO_CONF output will be set low when the WM8351 enters the OFF state and set
high on every transition from OFF to ACTIVE, re-triggering the external ‘genie’. Also, by default, the
internal control registers will be reset when the WM8351 enters the OFF state. This behaviour can be
changed using the RECONFIG_AT_ON register bit. If RECONFIG_AT_ON is set to 0, then the
control registers will not be reset when going into the OFF state, and the DO_CONF output will
remain set high after the first powering up of the chip, regardless of subsequent state transitions.
De-selection of RECONFIG_AT_ON should be used with caution, as this can potentially lead to
system failures in some applications. If RECONFIG_AT_ON is set to 0, and an OFF event occurs,
then it is possible that control registers will not be set to the intended start-up values when the
WM8351 subsequently returns to the ON state. The impact of this will depend upon the hardware
and software of the particular target application, and is not necessarily a risk in every instance.
Please contact Wolfson Applications support if further guidance is required on this topic.
Note that RECONFIG_AT_ON should never be set to 0 in Custom Modes 01, 10 or 11. Setting this
bit to 0 may result in erroneous behaviour and deviation from the custom configuration settings.
Under default settings, the control registers are always reset in the OFF state.
The register fields DO_CONF and RECONFIG_AT_ON are defined in Table 63.
ADDRESS
R6 (06h)
Interface
Control
BIT
LABEL
DEFAULT
12
CONFIG_D
ONE
0
Tells the system that the PIC micro has
completed its programming.
0 = Programming still to be done
1 = Programming complete
Only applies when CONFIG pins[1:0] = 00.
DESCRIPTION
11
RECONFIG
_AT_ON
1
Selects whether to reset the registers in the
OFF state and whether to reload the device
configuration from the PIC when an ON
event occurs.
0 = Do not reset registers in the OFF state.
Do not load configuration data when an ON
event occurs.
1 = Reset registers in the OFF state. Load
configuration from the PIC when an ON
event occurs.
Note that, in development mode, the device
configuration from the PIC is always loaded
when first powering up the chip.
This bit must always be set to default (1) in
Custom Modes 01, 10 and 11.
Table 63 Start-Up Control in Development Mode
Note: if the WM8351 enters the BACKUP state as a result of an undervoltage condition (see
Section 18), then the control registers will be reset, but DO_CONF will remain high. When the supply
voltage rises and device comes out of BACKUP, the DO_CONF output will still be high. If the
DO_CONF signal is used to trigger an external ‘genie’ device, then this may not work, as the
DO_CONF has remained high through the BACKUP state transition, and the WM8351 device will
become locked in the PRE-ACTIVE state when an ON event occurs.
This problem may be avoided by ensuring that the ‘genie’ monitors the LINE voltage in order to
recognise the undervoltage condition, and that it verifies the I2C Acknowledge signal on the
secondary interface (GPIO10 and GPIO11) to determine whether it can execute its programming
function.
14.4.3
CONFIGURING THE WM8351 IN DEVELOPMENT MODE
The WM8351 can be configured in Development mode by writing to control bits that determine its
startup behaviour. The locations of these register bits are shown in Table 64 below. A typical
configuration sequence would include writes to some or all of the registers listed. If none of the
highlighted bits in any given register needs to be changed from its default, then no write to that
register is recommended.
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The configuration bits include:
•
Duration control bits for the /RST reset signal (RSTB_TO)
•
GPIO pull-up / pull-down settings and debounce times (GPn_PD, GPn_PU, GPn_DB and
GP_DBTIME)
•
Alternate function and input/output selection for GPIO pins (GPn_FN, GPn_DIR and GPn_CFG)
•
Voltage settings for DC-DC converters and LDO regulators (DCn_VSEL and LDOn_VSEL)
•
Time slots for automatic start of all DC-DC converters, all LDO regulators and the Current Limit
Switch during startup (DCn_ENSLOT, LDOn_ENSLOT and LS_ENSLOT). Note that supplies
can be programmed to not start up automatically by setting the respective _ENSLOT bits to
0000.
Typically, the final step in the sequence is a write to register R6, in order to:
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•
Select the WM8351 device address on the primary control interface, using the DEV_ADDR bits.
•
Allow the WM8351 to proceed to startup. This is achieved by setting the CONFIG_DONE bit
(R6 bit 12) to 1.
•
Switch the control interface back to the primary interface (if desired), so that a host processor
can communicate with the WM8351. This is achieved by setting USE_DEV_PINS (R6 bit 15) to
0.
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REGISTER
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Select /RST duration
R3 (03h)
RSTB_TO
Unlock protected registers
R219 (DBh)
0013h
Alternate function and input/output selection for GPIO pins
R140 (8Ch)
GP3_FN
GP2_FN
GP1_FN
GP0_FN
R141 (8Dh)
GP7_FN
GP6_FN
GP5_FN
GP4_FN
R142 (8Eh)
GP11_FN
GP10_FN
GP9_FN
GP8_FN
R143 (8Fh)
GP12_FN
R128 (80h)
GPn_DB (n = 0 to 12)
R129 (81h)
GPn_PU (n = 0 to 12)
R130 (82h)
GPn_PD (n = 0 to 12)
R134 (86h)
GPn_DIR (n = 0 to 12)
R135 (87h)
GPn_CFG (n = 0 to 12)
Disable battery charger (only if battery type is not compatible with WM8351 charger)
R168 (A8h)
0
Re-lock protected registers
R219 (DBh)
FFFFh
Configure supply generation
R180 (B4h)
DC1_VSEL[6:0]
R181(B5h)
DC1_ENSLOT[3:0]
R183 (B7h)
DC2_ENSLOT[3:0]
R186 (BAh)
DC3_VSEL[6:0]
R187 (BBh)
DC3_ENSLOT 3:0]
R189 (BDh)
DC4_VSEL[6:0]
R190 (BEh)
DC4_ENSLOT[3:0]
R199 (C7h)
LS_ENSLOT[3:0]
R200 (C8h)
LDO1_VSEL[4:0]
R201 (C9h)
LDO1_ENSLOT[3:0]
R203 (CAh)
LDO2_VSEL[4:0]
R204 (CBh)
LDO2_ENSLOT[3:0]
R206 (CEh)
LDO3_VSEL[4:0]
R207 (CFh)
LDO3_ENSLOT[3:0]
R209 (D1h)
LDO4_VSEL[4:0]
R210 (D2h)
LDO4_ENSLOT[3:0]
Proceed to startup and hand over to host processor
R6 (06h)
0
DEV_ADDR
1
Table 64 Suggested Sequence of Register Writes for WM8351 Configuration in Development Mode
Note that configuration only includes registers that are required for starting up correctly. All other
register settings should be loaded after the WM8351 has started up.
Most of these control fields are described here within Section 14. See Section 11.6 for details of
Register Locking. See Section 20 for details of the GPIO configuration fields. See Section 17.7 for
details of the Battery Charger configuration.
When using the /RST signal to trigger configuration, writing to the _ENSLOT and RSTB_TO fields
can be omitted (the reset and power-up sequence has already taken place, so the write would have
no effect). However, additional writes to R13 or R176 should be added to enable the DC-DC
converters and LDO regulators one by one.
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14.5 CUSTOM MODES
The WM8351 provides three custom start-up modes. These are selected by setting the CONF1 and
CONF0 pins = 01, 10 or 11. The custom mode start-up sequences define the following parameters:
•
Polarity of the ON pin (Active low or high)
•
Configuration of the USB power source
•
Configuration of the Watchdog timer mode
•
Configuration of the Control Interface mode
•
Configuration of the 32kHz oscillator (enabled or disabled)
•
Configuration of the real-time-clock (enabled or disabled)
•
Configuration of LDO1
•
Selection of crystal oscillator detect mode (see Section 14.3.6)
•
Configuration of the voltage settings and start-up timeslots for DC-DC and LDO supplies
•
Configuration of GPIO pins
In Development Mode, the RECONFIG_AT_ON register bit (see Section 14.4.2) may be used to
control the device configuration behaviour. In Custom Modes 01, 10 or 11, the default setting
(RECONFIG_AT_ON = 1) must always be used. Setting this bit to 0 may result in erroneous
behaviour and deviation from the custom configuration settings.
The custom modes do not allow configuring the WM8351 in the OFF state. As a result, evaluation
and debugging in custom modes is limited.
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14.5.1
CONFIGURATION MODE 01
In Configuration Mode 01, the following general default settings apply:
PARAMETER
REGISTER SETTING
DESCRIPTION
ON polarity
ON_POL = 1
ON pin is Active Low
USB power source
USB_SLV_500MA = 1
Selects 500mA limit in USB slave
Watchdog timer
WDOG_MODE [1:0] = 00
Watchdog is disabled
Control Interface
SPI_3WIRE = 0
SPI_4WIRE = 0
SPI_CFG = 0
Control Interface is 2-wire mode
32kHz oscillator
OSC32K_ENA = 1
32kHz Oscillator is enabled
Real Time Clock
RTC_TICK_ENA = 1
RTC_CLKSRC = 0
Real Time Clock is enabled
LDO1
LDO1_PIN_MODE = 1
LDO1_PIN_EN = 0
LDO1 enabled at all times
Crystal detect
mode
Crystal detect mode is not enabled.
The default voltages and the power-up sequence for all DC-DCs and LDOs in Configuration Mode 01
are shown below in Table 65 and Figure 66.
The time delay between each time slot is approximately 1.28ms.
Note that the Limit Switch is not enabled automatically in Configuration Mode 01; as a result, the
Limit Switch remains open when the WM8351 enters the ACTIVE state.
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SUPPLY
REGISTER SETTING
DESCRIPTION
DCDC1
DC1_ENSLOT [3:0] = 0011
DC1_VSEL [6:0] = 000_1110
Third timeslot
1.2V
DCDC2
DC2_ENSLOT [3:0] = 0000
Disabled
DCDC3
DC3_ENSLOT [3:0] = 0001
DC3_VSEL [6:0] = 010_0110
First timeslot
1.8V
DCDC4
DC4_ENSLOT [3:0] = 0010
DC4_VSEL [6:0] = 110_0010
Second timeslot
3.3V
LDO1
LDO1_ENSLOT [3:0] = 0000
LDO1_VSEL [4:0] = 0_0110
(See note below)
1.2V
LDO2
LDO2_ENSLOT [3:0] = 0011
LDO2_VSEL [4:0] = 1_0000
Third timeslot
1.8V
LDO3
LDO3_ENSLOT [3:0] = 0010
LDO3_VSEL [4:0] =1_1111
Second timeslot
3.3V
LDO4
LDO4_ENSLOT [3:0] = 0010
LDO4_VSEL [4:0] = 0_1010
Second timeslot
1.4V
Table 65 Default Supply Voltages / Power-up Sequence for Configuration Mode 01
Note: In this Configuration Mode, LDO1 is enabled at all times. Therefore, the setting of
LDO1_ENSLOT has no effect.
Figure 66 Power-up Sequence - Configuration Mode 01
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The default GPIO settings for configuration mode 01 are shown below in Table 66.
GPIO PIN
POWER
DOMAIN
DEFAULT GPIO
FUNCTION
DEFAULT
DIRECTION
DEFAULT PULL-UP /
PULL-DOWN
DEFAULT
DE-BOUNCE
GPIO0
VRTC
GP0_FN [3:0] = 0000
GPIO
GP0_DIR = 1
GP0_CFG =1
Input, Active High
GP0_PD=0
GP0_PU=0
Normal Mode
GP0_DB = 1
Debounce enabled
GPIO1
VRTC
GP1_FN [3:0] = 0000
GPIO
GP1_DIR = 1
GP1_CFG =1
Input, Active High
GP1_PD=0
GP1_PU=0
Normal Mode
GP1_DB = 1
Debounce enabled
GPIO2
VRTC
GP2_FN [3:0] = 0011
32KHZ
GP2_DIR = 0
GP2_CFG =1
Output, Open Drain
GP2_PD=0
GP2_PU=0
Normal Mode
GP2_DB = 1
Debounce enabled
GPIO3
VRTC
GP3_FN [3:0] = 0000
GPIO
GP3_DIR = 1
GP3_CFG =1
Input, Active High
GP3_PD=0
GP3_PU=0
Normal Mode
GP3_DB = 1
Debounce enabled
GPIO4
DBVDD
GP4_FN [3:0] = 0000
GPIO
GP4_DIR = 1
GP4_CFG =1
Input, Active High
GP4_PD=0
GP4_PU=0
Normal Mode
GP4_DB = 1
Debounce enabled
GPIO5
DBVDD
GP5_FN [3:0] = 0001
L_PWR1
GP5_DIR = 1
GP5_CFG =0
Input, Active Low
GP5_PD=0
GP5_PU=0
Normal Mode
GP5_DB = 1
Debounce enabled
GPIO6
DBVDD
GP6_FN [3:0] = 0001
L_PWR2
GP6_DIR = 1
GP6_CFG =0
Input, Active Low
GP6_PD=0
GP6_PU=0
Normal Mode
GP6_DB = 1
Debounce enabled
GPIO7
DBVDD
GP7_FN [3:0] = 0001
L_PWR3
GP7_DIR = 1
GP7_CFG =0
Input, Active Low
GP7_PD=0
GP7_PU=0
Normal Mode
GP7_DB = 1
Debounce enabled
GPIO8
DBVDD
GP8_FN [3:0] = 0011
/BATT_FAULT
GP8_DIR = 0
GP8_CFG =0
Output, CMOS
GP8_PD=0
GP8_PU=0
Normal Mode
GP8_DB = 1
Debounce enabled
GPIO9
DBVDD
GP9_FN [3:0] = 0001
/VCC_FAULT
GP9_DIR = 0
GP9_CFG =0
Output, CMOS
GP9_PD=0
GP9_PU=0
Normal Mode
GP9_DB = 1
Debounce enabled
GPIO10
LINE
GP10_FN [3:0] = 0000
GPIO
GP10_DIR = 1
GP10_CFG =1
Input, Active High
GP10_PD=0
GP10_PU=0
Normal Mode
GP10_DB = 1
Debounce enabled
GPIO11
LINE
GP11_FN [3:0] = 0000
GPIO
GP11_DIR = 1
GP11_CFG =1
Input, Active High
GP11_PD=0
GP11_PU=0
Normal Mode
GP11_DB = 1
Debounce enabled
GPIO12
LINE
GP12_FN [3:0] = 0011
LINE_SW
GP12_DIR = 0
GP12_CFG =0
Output, CMOS
GP12_PD=0
GP12_PU=0
Normal Mode
GP12_DB = 1
Debounce enabled
Table 66 Default GPIO Settings for Configuration Mode 01
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14.5.2
CONFIGURATION MODE 10
In Configuration Mode 10, the following general default settings apply:
PARAMETER
REGISTER SETTING
DESCRIPTION
ON polarity
ON_POL = 1
ON pin is Active Low
USB power source
USB_SLV_500MA = 1
Selects 500mA limit in USB slave
Watchdog timer
WDOG_MODE [1:0] = 01
Watchdog set to Interrupt on
Timeout
Control Interface
SPI_3WIRE = 0
SPI_4WIRE = 0
SPI_CFG = 0
Control Interface is 2-wire mode
32kHz oscillator
OSC32K_ENA = 1
32kHz Oscillator is enabled
Real Time Clock
RTC_TICK_ENA = 1
RTC_CLKSRC = 0
Real Time Clock is enabled, driven
by the internal 32kHz oscillator
LDO1
LDO1_PIN_MODE = 0
LDO1_PIN_EN = 0
LDO1 controlled as normal via
register bits
Crystal detect
mode
Crystal detect mode is not enabled.
The default voltages and the power-up sequence for all DC-DCs and LDOs in Configuration Mode 10
are shown below in Table 67 and Figure 67.
The time delay between each time slot is approximately 1.28ms.
Note that the Limit Switch is not enabled automatically in Configuration Mode 10; as a result, the
Limit Switch remains open when the WM8351 enters the ACTIVE state.
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SUPPLY
REGISTER SETTING
DESCRIPTION
DCDC1
DC1_ENSLOT [3:0] = 0010
DC1_VSEL [6:0] = 001_1010
Second timeslot
1.5V
DCDC2
DC2_ENSLOT [3:0] = 0000
Disabled
DCDC3
DC3_ENSLOT [3:0] = 0001
DC3_VSEL [6:0] = 101_0110
First timeslot
3.0V
DCDC4
DC4_ENSLOT [3:0] = 0011
DC4_VSEL [6:0] = 010_0110
Third timeslot
1.8V
LDO1
LDO1_ENSLOT [3:0] = 0001
LDO1_VSEL [4:0] = 1_1100
First timeslot
3.0V
LDO2
LDO2_ENSLOT [3:0] = 0011
LDO2_VSEL [4:0] = 1_0000
Third timeslot
1.8V
LDO3
LDO3_ENSLOT [3:0] = 0000
LDO3_VSEL [4:0] = 1_0101
Disabled
2.3V
LDO4
LDO4_ENSLOT [3:0] = 0000
LDO4_VSEL [4:0] = 1_1010
Disabled
2.8V
Table 67 Default Supply Voltages / Power-up Sequence for Configuration Mode 10
Figure 67 Power-up Sequence - Configuration Mode 10
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The default GPIO settings for configuration mode 10 are shown below in Table 68.
GPIO PIN
POWER
DOMAIN
DEFAULT GPIO
FUNCTION
DEFAULT
DIRECTION
DEFAULT PULL-UP /
PULL-DOWN
DEFAULT
DE-BOUNCE
GPIO0
VRTC
GP0_FN [3:0] = 0000
GPIO
GP0_DIR = 0
GP0_CFG =0
Output, CMOS
GP0_PD=0
GP0_PU=0
Normal Mode
GP0_DB = 1
Debounce enabled
GPIO1
VRTC
GP1_FN [3:0] = 0001
PWR_ON
GP1_DIR = 1
GP1_CFG =1
Input, Active High
GP1_PD=0
GP1_PU=0
Normal Mode
GP1_DB = 1
Debounce enabled
GPIO2
VRTC
GP2_FN [3:0] = 0011
32kHz
GP2_DIR = 0
GP2_CFG =1
Output, Open Drain
GP2_PD=0
GP2_PU=0
Normal Mode
GP2_DB = 1
Debounce enabled
GPIO3
VRTC
GP3_FN [3:0] = 0001
PWR_ON
GP3_DIR = 1
GP3_CFG =0
Input, Active Low
GP3_PD=0
GP3_PU=0
Normal Mode
GP3_DB = 1
Debounce enabled
GPIO4
DBVDD
GP4_FN [3:0] = 0011
HIBERNATE Level
GP4_DIR = 1
GP4_CFG =1
Input, Active High
GP4_PD=1
GP4_PU=0
Pull-down
GP4_DB = 1
Debounce enabled
GPIO5
DBVDD
GP5_FN [3:0] = 0000
GPIO
GP5_DIR = 1
GP5_CFG =1
Input, Active High
GP5_PD=0
GP5_PU=0
Normal Mode
GP5_DB = 1
Debounce enabled
GPIO6
DBVDD
GP6_FN [3:0] = 0000
GPIO
GP6_DIR = 1
GP6_CFG =1
Input, Active High
GP6_PD=0
GP6_PU=0
Normal Mode
GP6_DB = 1
Debounce enabled
GPIO7
DBVDD
GP7_FN [3:0] = 0000
GPIO
GP7_DIR = 1
GP7_CFG =1
Input, Active High
GP7_PD=0
GP7_PU=0
Normal Mode
GP7_DB = 1
Debounce enabled
GPIO8
DBVDD
GP8_FN [3:0] = 0000
GPIO
GP8_DIR = 1
GP8_CFG =1
Input, Active High
GP8_PD=1
GP8_PU=0
Pull-down
GP8_DB = 1
Debounce enabled
GPIO9
DBVDD
GP9_FN [3:0] = 0000
GPIO
GP9_DIR = 0
GP9_CFG =0
Output, CMOS
GP9_PD=0
GP9_PU=0
Normal Mode
GP9_DB = 1
Debounce enabled
GPIO10
LINE
GP10_FN [3:0] = 0000
GPIO
GP10_DIR = 0
GP10_CFG =1
Output, Open Drain
GP10_PD=0
GP10_PU=0
Normal Mode
GP10_DB = 1
Debounce enabled
GPIO11
LINE
GP11_FN [3:0] = 0010
/WAKEUP
GP11_DIR = 1
GP11_CFG =1
(see note)
GP11_PD=0
GP11_PU=0
Normal Mode
GP11_DB = 1
Debounce enabled
GPIO12
LINE
GP12_FN [3:0] = 0000
GPIO
GP12_DIR = 0
GP12_CFG =0
Output, CMOS
GP12_PD=0
GP12_PU=0
Normal Mode
GP12_DB = 1
Debounce enabled
Note: The alternate GPIO functions PWR_ON and /WAKEUP are system wakeup events. The debounce time of these
functions are determined by GP_DBTIME[1:0] + 40ms
Table 68 Default GPIO Settings for Configuration Mode 10
Note that setting GP11_CFG = 1 results in Active Low function for /WAKEUP. In most cases, setting
GPn_CFG = 1 results in Active High function, but /MR, /WAKEUP and /LDO_ENA are exceptions to
this. See Section 20.
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14.5.3
CONFIGURATION MODE 11
In Configuration Mode 11, the following general default settings apply:
PARAMETER
REGISTER SETTING
DESCRIPTION
ON polarity
ON_POL = 1
ON pin is Active Low
USB power source
USB_SLV_500MA = 1
Selects 500mA limit in USB slave
Watchdog timer
WDOG_MODE [1:0] = 00
Watchdog is disabled
Control Interface
SPI_3WIRE = 0
SPI_4WIRE = 0
SPI_CFG = 0
Control Interface is 2-wire mode
32kHz oscillator
OSC32K_ENA = 1
32kHz Oscillator is enabled
Real Time Clock
RTC_TICK_ENA = 1
RTC_CLKSRC = 0
Real Time Clock is enabled, driven
by the internal 32kHz oscillator
LDO1
LDO1_PIN_MODE = 0
LDO1_PIN_EN = 0
LDO1 controlled as normal via
register bits
Crystal detect
mode
Crystal detect mode is enabled.
(/RST output is held low until
32kHz oscillator is valid.)
The default voltages and the power-up sequence for all DC-DCs and LDOs in configuration mode 11
are shown below in Table 69 and Figure 68.
The time delay between each time slot is approximately 1.28ms.
Note that the Limit Switch is not enabled automatically in Configuration Mode 11; as a result, the
Limit Switch remains open when the WM8351 enters the ACTIVE state.
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SUPPLY
REGISTER SETTING
DESCRIPTION
DCDC1
DC1_ENSLOT [3:0] = 0001
DC1_VSEL [6:0] = 000_1110
First timeslot
1.2V
DCDC2
DC2_ENSLOT [3:0] = 0000
Disabled
DCDC3
DC3_ENSLOT [3:0] = 0010
DC3_VSEL [6:0] = 010_0110
Second timeslot
1.8V
DCDC4
DC4_ENSLOT [3:0] = 0101
DC4_VSEL [6:0] = 110_0010
Fifth timeslot
3.3V
LDO1
LDO1_ENSLOT [3:0] = 0011
LDO1_VSEL [4:0] = 0_0110
Third timeslot
1.2V
LDO2
LDO2_ENSLOT [3:0] = 0000
LDO2_VSEL [4:0] = 1_0110
Disabled
2.4V
LDO3
LDO3_ENSLOT [3:0] = 0000
LDO3_VSEL [4:0] = 1_1001
Disabled
2.7V
LDO4
LDO4_ENSLOT [3:0] = 0100
LDO4_VSEL [4:0] = 1_1010
Fourth timeslot
2.8V
Table 69 Default Supply Voltages / Power-up Sequence for Configuration Mode 11
Figure 68 Power-up Sequence - Configuration Mode 11
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The default GPIO settings for configuration mode 11 are shown below in Table 70.
GPIO PIN
POWER
DOMAIN
DEFAULT GPIO
FUNCTION
DEFAULT
DIRECTION
DEFAULT PULL-UP /
PULL-DOWN
DEFAULT
DE-BOUNCE
GPIO0
VRTC
GP0_FN [3:0] = 0000
GPIO
GP0_DIR = 1
GP0_CFG =1
Input, Active High
GP0_PD=0
GP0_PU=0
Normal Mode
GP0_DB = 0
Debounce enabled
GPIO1
VRTC
GP1_FN [3:0] = 0001
PWR_ON
GP1_DIR = 1
GP1_CFG =0
Input, Active Low
GP1_PD=0
GP1_PU=0
Normal Mode
GP1_DB = 1
Debounce enabled
GPIO2
VRTC
GP2_FN [3:0] = 0011
32kHz
GP2_DIR = 0
GP2_CFG =1
Output, Open Drain
GP2_PD=0
GP2_PU=0
Normal Mode
GP2_DB = 1
Debounce enabled
GPIO3
VRTC
GP3_FN [3:0] = 0000
GPIO
GP3_DIR = 1
GP3_CFG =1
Input, Active High
GP3_PD=0
GP3_PU=0
Normal Mode
GP3_DB = 1
Debounce enabled
GPIO4
DBVDD
GP4_FN [3:0] = 0001
/MR
GP4_DIR = 1
GP4_CFG =1
(see note)
GP4_PD=0
GP4_PU=1
Pull-up
GP4_DB = 1
Debounce enabled
GPIO5
DBVDD
GP5_FN [3:0] = 0000
GPIO
GP5_DIR = 1
GP5_CFG =1
Input, Active High
GP5_PD=0
GP5_PU=0
Normal Mode
GP5_DB = 1
Debounce enabled
GPIO6
DBVDD
GP6_FN [3:0] = 0000
GPIO
GP6_DIR = 1
GP6_CFG =1
Input, Active High
GP6_PD=0
GP6_PU=0
Normal Mode
GP6_DB = 1
Debounce enabled
GPIO7
DBVDD
GP7_FN [3:0] = 0000
GPIO
GP7_DIR = 1
GP7_CFG =1
Input, Active High
GP7_PD=0
GP7_PU=0
Normal Mode
GP7_DB = 1
Debounce enabled
GPIO8
DBVDD
GP8_FN [3:0] = 0000
GPIO
GP8_DIR = 1
GP8_CFG =1
Input, Active High
GP8_PD=0
GP8_PU=0
Normal Mode
GP8_DB = 1
Debounce enabled
GPIO9
DBVDD
GP9_FN [3:0] = 0000
GPIO
GP9_DIR = 1
GP9_CFG =1
Input, Active High
GP9_PD=0
GP9_PU=0
Normal Mode
GP9_DB = 1
Debounce enabled
GPIO10
LINE
GP10_FN [3:0] = 0011
CH_IND
GP10_DIR = 0
GP10_CFG =1
Output, Open Drain
GP10_PD=0
GP10_PU=0
Normal Mode
GP10_DB = 1
Debounce enabled
GPIO11
LINE
GP11_FN [3:0] = 0010
/WAKEUP
GP11_DIR = 1
GP11_CFG =1
(see note)
GP11_PD=0
GP11_PU=0
Normal Mode
GP11_DB = 1
Debounce enabled
GPIO12
LINE
GP12_FN [3:0] = 0011
LINE_SW
GP12_DIR = 0
GP12_CFG =0
Output, CMOS
GP12_PD=0
GP12_PU=0
Normal Mode
GP12_DB = 1
Debounce enabled
Note: The alternate GPIO functions PWR_ON and /WAKEUP are system wakeup events. The debounce time of these
functions are determined by GP_DBTIME[1:0] + 40ms
Table 70 Default GPIO Settings for Configuration Mode 11
Note that setting GP4_CFG = 1 results in Active Low function for /MR. Also, setting GP11_CFG = 1
results in Active Low function for /WAKEUP. In most cases, setting GPn_CFG = 1 results in Active
High function, but /MR, /WAKEUP and /LDO_ENA are exceptions to this. See Section 20.
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14.6 CONFIGURING THE DC-DC CONVERTERS
The configuration of the DC-DC converters is described in the following sections. Some of the control
fields form part of the Custom Mode configuration settings and therefore will not require to be set in
software in some applications.
14.6.1
DC-DC CONVERTER ENABLE
The DC-DC Converters can be enabled in software using the register fields defined in Table 71. All
DC-DC converters include a soft-start feature that helps to reduce the inductor current at start up. In
order to further reduce supply in-rush current, individual converters should be programmed to start in
different time slots within the start-up sequence.
In the WM8351 ACTIVE state, the DC-DC Converters can be enabled in software using the
DCn_ENA bits. Setting these bits whilst in the Pre-Active state (see Figure 65) will not immediately
enable the corresponding DC-DC converter; these bits will only become effective once the WM8351
has reached the ACTIVE state.
Each Converter may be programmed to switch on in a selected timeslot within the start-up sequence.
The WM8351 will set the DCn_ENA field for any DC-DC converter that is enabled during the start-up
sequence. Note that setting the DCn_ENSLOT fields in software is only relevant to the Development
Mode, as these fields are assigned preset values in each of the Custom Modes.
Each Converter may be programmed to switch off in a selected timeslot within the shutdown
sequence. If a Converter is not allocated to one of the 14 shutdown timeslots, it will be disabled when
the WM8351 enters the OFF state.
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Note: n is a number between 1 and 6 that identifies the individual DC-DC converter
R13 (0Dh) or
0,1,2,3
DCn_ENA
R176 (B0h)
Dependant on
CONFIG[1:0]
settings
DCDCn converter enable
0 = disabled
1 = enabled
Note: internal conditions may prevent
the converter from actually switching on
- see DCDC/LDO Status register for
actual converter status.
Note: These bits can be accessed through R13 or through R176. Reading from or writing to either
register location has the same effect.
R181 (B5h) for
DC-DC1
13:10
DCn_ENSLO Dependant on
T [3:0]
CONFIG[1:0]
settings
Time slot for DC-DCn start-up
0000 = Disabled (do not start up)
0001 = Start-up in time slot 1
… (total 14 slots available)
1110 = Start-up in time slot 14
1111 = Start up on entering ACTIVE
DCn_SDSLO
T [3:0]
Time slot for DC-DCn shutdown.
0000 = Shut down on entering OFF
0001 = Shutdown in time slot 1
…. (total 14 slots available)
1110 = Shutdown in time slot 14
1111 = Shut down on entering OFF
R184 (B8h) for
DC-DC2
R187 (BBh) for
DC-DC3
9:6
0000
R190 (BEh) for
DC-DC4
Note: n is number between 1 and 4 that identifies the individual DC-DC converter
Table 71 Enabling and Disabling the DC-DC Converters
14.6.2
CLOCKING
The DC-DC converters are controlled by an internally generated clock signal from the RC Oscillator
with a constant frequency of around 2.0MHz for DC-DC 1, 3 and 4, and a constant frequency of
around 1.0MHz for DC-DC 2.
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14.6.3
DC-DC BUCK (STEP-DOWN) CONVERTER CONTROL
DC-DC Converters 1, 3 and 4 are buck converters which can be configured to operate in different
operating modes using the register bits described in Table 72.
In Active mode, the DC-DC Converters operate to their highest level of performance. The DC-DC
Converters will automatically select PWM or Pulse-Skipping operation according to the load
condition. This enables the power efficiency to be maximised across a wide range of load conditions.
It is possible to force the Converters to use the higher performance PWM mode; in this mode, pulseskipping is disabled and the output voltage is regulated by switching at a constant frequency which
improves the transient response at light loads.
In Standby/Hysteretic Mode, the DC-DC Converters disable some of the internal control circuitry in
order to reduce power consumption. The load regulation may be degraded in this mode of operation.
The efficiency data in Section 9.2.1 shows the conditions under which Standby Mode can offer better
efficiency than Active Mode.
In LDO Mode, the DC-DC Converters are reconfigured as low power LDOs.
When DCn_SLEEP = 0, the corresponding DCn_ACTIVE register bit selects between Active and
Standby/Hysteretic modes for the associated DC-DC converter.
The DCn_SLEEP register bits control the selection of LDO Mode. Setting DCn_SLEEP = 1 selects
LDO Mode. This bit takes precedence over the corresponding DCn_ACTIVE bit.
ADDRESS
R177 (B1h)
DC-DC Active
Options
R178 (B2h)
DC-DC Sleep
Options
BIT
LABEL
DEFAULT
0
DC1_ACTIVE
1
2
DC3_ACTIVE
1
3
DC4_ACTIVE
1
0
DC1_SLEEP
0
2
DC3_SLEEP
0
3
DC4_SLEEP
0
DESCRIPTION
DC-DCn Active mode
0 = Select Standby mode
1 = Select Active mode
DC-DCn Sleep Mode
0 = Normal DC-DC operation
1 = Select LDO mode
Note: n is either 1, 3 or 4 and identifies the individual DC-DC converter
R248 (F8h)
DCDC1 Test
Controls
4
DC1_FORCE_
PWM
0
Force DC-DC1 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
R250 (FAh)
DCDC3 Test
Controls
4
DC3_FORCE_
PWM
0
Force DC-DC3 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
R251 (FBh)
DCDC4 Test
Controls
4
DC4_FORCE_
PWM
0
Force DC-DC4 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
Table 72 Operating Mode Control for DC-DC Converters 1, 3 and 4
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DC-DC Converters 1, 3 and 4 can also be controlled by the device HIBERNATE bit, or by hardware
input signals L_PWR1, L_PWR2 and L_PWR3. Several GPIO pins can be assigned as L_PWR pins.
Each converter can be assigned to one of these three signals, or else to the device HIBERNATE bit.
The signals are active high and each converter’s response to the selected signal is programmable as
defined in Table 73.
Note that, when a GPIO pin is configured as a Hibernate input pin, and this input is asserted, then all
DC-DC Converters will be placed in Hibernate mode.
In order to use GPIO pins as L_PWR pins, they must be configured by setting the respective
GPn_FN, and GPn_DIR bits to the appropriate value (see Section 20).
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R182 (B6h) for
DC-DC1
14:12
DCn_HIB_M
ODE [2:0]
001
DC-DCn Hibernate behaviour:
000 = Use current settings (no change)
001 = Select voltage image settings
010 = Force standby mode
011 = Force standby mode and voltage
image settings
100 = Force LDO mode
101 = Force LDO mode and voltage
image settings
110 = Reserved
111 = Disable output
9:8
DCn_HIB_T
RIG [1:0]
00
DC-DCn Hibernate signal select
00 = HIBERNATE register bit
01 = L_PWR1
10 = L_PWR2
11 = L_PWR3
Note that Hibernate is also selected
when a GPIO Hibernate input is
asserted.
R188 (BCh) for
DC-DC3
R191 (BFh) for
DC-DC4
Note: n is either 1, 3 or 4 and identifies the individual DC-DC converter
Table 73 Low-Power Mode Control for DC-DC Converters 1, 3 and 4
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The default output voltage for DC-DC Converters 1, 3 and 4 is set by writing to the DCn_VSEL
register bits. The ‘image’ voltage settings DCn_VIMG are alternate values that may be invoked when
the HIBERNATE software or hardware control is asserted as described above.
The DC-DC Converters 1, 3 and 4 are dynamically programmable - the output voltage may be
adjusted in software at any time. These Converters are buck (step-down) converters; their output
voltage can therefore be lower than the input voltage, but cannot be higher.
ADDRESS
R180 (B4h) for
DC-DC1
BIT
6:0
LABEL
DCn_VSEL
[6:0]
DEFAULT
Dependant on
CONFIG[1:0]
settings
R186 (BAh) for
DC-DC3
110 0110 = 3.4V
110 0010 = 3.3V
101 0110 = 3.0V
100 1110 = 2.8V
……
010 0110 = 1.8V
000 1110 = 1.2V
000 0110 = 1.0V
000 0000 = 0.85V
R189 (BDh) for
DC-DC4
R182 (B6h) for
DC-DC1
DESCRIPTION
DC-DCn Converter output voltage
settings in 25mV steps.
Maximum output = 3.4V.
6:0
DCn_VIMG
[6:0]
000 0110
R188 (BCh) for
DC-DC3
DC-DCn Converter output image voltage
settings in 25mv steps.
Maximum output = 3.4V.
110 0110 = 3.4V
110 0010 = 3.3V
101 0110 = 3.0V
100 1110 = 2.8V
……
010 0110 = 1.8V
000 1110 = 1.2V
000 0110 = 1.0V
000 0000 = 0.85V
R191 (BFh) for
DC-DC4
Note: n is either 1, 3 or 4 and identifies the individual DC-DC converter
Table 74 Output Voltage Control for DC-DC Converters 1, 3 and 4
When the DC-DC Converters 1, 3 and 4 are disabled, the output can be set to float or else the
outputs can be actively discharged through internal resistors. This feature is controlled using the
register bits described in Table 75.
ADDRESS
R180 (B4h) for
DC-DC1
R186 (BAh) for
DC-DC3
BIT
LABEL
DEFAULT
10
DCn_OPFLT
0
DESCRIPTION
Enable discharge of DC-DCn outputs
when DC-DCn is disabled
0 = Enabled - Output to be discharged
1 = Disabled - Output is left floating
R189 (BDh) for
DC-DC4
Note: n is either 1, 3 or 4 and identifies the individual DC-DC converter
Table 75 Output Float Control for DC-DC Converters 1, 3 and 4
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A summary of the Mode Control and Voltage Control for DC-DC Converter 1 is provided in Table 76.
Note that “Hibernate” in Table 76 refers to a GPIO Hibernate input or to the applicable Hibernate
signal selected by the DC1_HIB_TRIG field.
The equivalent logic applies for DC-DC 3 and 4. Note that the DC-DC Converters must also be
enabled as described in Table 71.
HIBERNATE
DC1_HIB_MODE
DC1_SLEEP
DC1_ACTIVE
OPERATING
MODE
OUTPUT
VOLTAGE
DC1_VSEL
0
X
0
0
Standby/Hysteretic
0
X
0
1
Active
DC1_VSEL
0
X
1
X
LDO Mode
DC1_VSEL
1
000
DC1_VSEL
001
0
0
Standby/Hysteretic
0
1
Active
DC1_VSEL
1
X
LDO Mode
DC1_VSEL
DC1_VIMG
0
0
Standby/Hysteretic
0
1
Active
DC1_VIMG
1
X
LDO Mode
DC1_VIMG
010
X
X
Standby/Hysteretic
DC1_VSEL
011
X
X
Standby/Hysteretic
DC1_VIMG
100
X
X
LDO Mode
DC1_VSEL
101
X
X
LDO Mode
DC1_VIMG
110
X
X
Disabled
N/A
111
X
X
Disabled
N/A
Table 76 DC1 Converter Operating Mode Selection
14.6.4
DC-DC BOOST (STEP-UP) CONVERTER CONTROL
DC-DC Converter 2 is a boost converter which can be configured to operate in different operating
modes, using the register bits described in Table 77.
In Switch mode, the DC-DC Converter acts as a switch between VP2 and L2. The switch is enabled
(closed) by setting DC2_ENA = 1. The switch is disabled (opened) by setting DC2_ENA = 0. Note
that the switch voltage source on VP2 must be >1.2V to ensure reliable operation.
In Boost mode, the DC-DC Converter operates as a step-up converter, employing current-mode
architecture, capable of powering LED lights. The output voltage can be higher than the input
voltage, but cannot be lower. Different configurations of voltage feedback are available in boost
mode, to control the output voltage in different ways. The voltage feedback mode is selected by the
DC2_FBSRC register field.
When DC2_FBSRC = 00, the converter’s output voltage is set by two external resistors connected to
FB2. See Section 29 for Applications Information covering the selection of suitable components.
When DC2_FBSRC = 01, the converter uses the ISINKA pin as feedback and adjusts its output
voltage in order to achieve the required ISINKA current.
When DC2_FBSRC = 11, the converter’s output voltage is set by two internal resistors, resulting in a
fixed 5V output, suitable for USB interfaces.
The current-controlled configuration using ISINKA is intended for controlling a string of seriallyconnected LEDs driven by the DC-DC boost converter. See Table 97 for a definition of the CS1_ISEL
register field which determines the required ISINKA current. In this mode, external resistors
connected on the FB2 pin determine the maximum output voltage. See Section 29 for Applications
Information covering the selection of suitable components.
In all configurations, the input pin VP2 must be externally wired to one of the supply rails, BATT or
LINE. Using LINE has the advantage that the converters can operate when the battery is flat,
defective or absent. Note that VP2 should not be connected to the USB supply rail.
The DC2_RMPH and DC2_RMPL bits defined in Table 77 should be set according to the desired
output voltage in order to optimise the transient response of the converter. Selecting a different value
could result in sub-harmonic oscillation of the converter.
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The DC2_ILIM bits defined in Table 77 should be set according to the intended output load
conditions.
ADDRESS
BIT
R183 (B7h)
DC-DC2 Control
14
DC2_MODE
LABEL
DEFAULT
0
DC-DC2 Converter Mode
0 = boost mode
1 = switch mode
DESCRIPTION
6
DC2_ILIM
0
DC-DC2 peak current limit select
0 = Higher peak current
1 = Lower peak current
4:3
DC2_RMPH
DC2_RMPL
01
DC-DC2 compensation ramp
{DC2_RMPH, DC2_RMPL}
00 = 20V < VOUT ≤ 30V
01 = 10V < VOUT ≤ 20V
10 = 5V < VOUT ≤ 10V
11 = VOUT ≤ 5V (will be chosen
automatically if DC2_FBSRC=11)
1:0
DC2_FBSRC
[1:0]
00
DC-DCn voltage feedback selection
00 = voltage feedback (using external
resistor divider on pin FBn)
01 = current sink ISINKA used as
feedback
10 = Reserved
11 = voltage feedback (using internal
resistor divider on pin USB)
Table 77 Operating Mode Control for DC-DC Converter 2
DC-DC Converter 2 can also be controlled by the device HIBERNATE bit, or by hardware input
signals L_PWR1, L_PWR2 and L_PWR3. Several GPIO pins can be assigned as L_PWR pins. The
converter can be assigned to one of these three signals, or else to the device HIBERNATE bit. The
signals are active high and the converter’s response to the selected signal is programmable as
defined in Table 78.
Note that, when a GPIO pin is configured as a Hibernate input pin, and this input is asserted, then all
DC-DC Converters will be placed in Hibernate mode.
In order to use GPIO pins as L_PWR pins, they must be configured by setting the respective
GPn_FN, and GPn_DIR bits to the appropriate value (see Section 20).
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ADDRESS
R183 (B7h)
DC-DC2
Control
BIT
LABEL
DEFAULT
12
DC2_HIB_MO
DE
0
DC-DC2 Hibernate behaviour:
0 = Continue as in Active state
1 = Disable converter output
DESCRIPTION
9:8
DC2_HIB_TRI
G [1:0]
00
DC-DC2 Hibernate signal select
00 = HIBERNATE register bit
01 = L_PWR1
10 = L_PWR2
11 = L_PWR3
Note that Hibernate is also selected
when a GPIO Hibernate input is
asserted.
Table 78 Hibernate Mode Control for DC-DC Converter 2
14.6.5
INTERRUPTS AND FAULT PROTECTION
Each DC-DC Converter is monitored for voltage accuracy and fault conditions. An undervoltage
condition is set if the voltage falls below 95% of the required level. The action taken in response to a
fault condition can be set independently for each DC-DC Converter, as described in Table 79.
The DCn_ERRACT fields configure the fault response to disable the respective converter or to shut
down the entire system if desired. In addition, DC-DC Converter fault conditions also generate a
second-level interrupt (see Section 24).
To prevent false alarms during short current surges, faults are only signalled if the fault condition
persists. When a DC-DC Converter is started up, any initial fault condition is ignored until the
Converter has been allowed time to settle. The time for which any fault condition is ignored is set by
the PUTO register field, as described in Table 79.
ADDRESS
R181 (B5h) for
DC-DC1
BIT
LABEL
DEFAULT
15:14
DCn_ERRAC
T [1:0]
00
Action to take on DC-DCn fault (as well
as generating an interrupt):
00 = ignore
01 = shut down converter
10 = shut down system
11 = reserved (shut down system)
13:12
PUTO [1:0]
00
Power up time out value for all
converters
00 = 0.5ms
01 = 2ms
10 = 32ms
11 = 256ms
R184 (B8h) for
DC-DC2
DESCRIPTION
R187 (BBh) for
DC-DC3
R190 (BEh) for
DC-DC4
R177 (B1h)
DCDC Active
options
Note: n is a number between 1 and 4 that identifies the individual DC-DC converter
Table 79 Fault Responses for DC-DC Converters
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The DC-DC Converters and the LDO Regulators have a first-level interrupt, UV_INT (see
Section 24). This comprises second-level interrupts from each of the DC-DC Converters and the
LDO Regulators.
Each DC-DC Converter has a dedicated second-level interrupt which indicates an under-voltage
condition. These can be masked by setting the applicable mask bit as defined in Table 80.
ADDRESS
BIT
R28 (1Ch)
Under Voltage
Interrupt Status
3
UV_DC4_EINT
DCDC4 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
2
UV_DC3_EINT
DCDC3 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
1
UV_DC2_EINT
DCDC2 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
0
UV_DC1_EINT
DCDC1 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
“IM_” + name of respective
bit in R28
Mask bits for DC-DC converter undervoltage interrupts
Each of these bits masks the respective
bit in R28 when it is set to 1 (e.g.
UV_DC1_EINT in R28 does not trigger a
UV_INT interrupt when
IM_UV_DC1_EINT in R36 is set).
R36 (24h)
Under Voltage
Interrupt Mask
as in
R28
LABEL
DESCRIPTION
Note: there is no over-current fault condition for converter 2.
Table 80 DC-DC Converter Interrupts
The status of the DC-DC Converters can be indicated and monitored externally via a GPIO pin
configured as /VCC_FAULT (see Section 20). When a GPIO pin is configured as /VCC_FAULT
output, a logic low level on this pin indicates that there is a fault condition on one of the LDO
Regulators, DC-DC Converters, or the Current Limit switch.
The /VCC_FAULT output is configurable by the control fields in Register R215. The fields described
in Table 81 determine which of the DC-DCs contribute to the /VCC_FAULT indication. An
undervoltage or overvoltage condition on any unmasked DC-DC Converter will cause the
/VCC_FAULT output to be set to logic low.
ADDRESS
R215 (D7h)
VCC_FAULT
BIT
LABEL
DEFAULT
DESCRIPTION
3
DC4_FAULT
0
DCDC4 fault mask for the
/VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
2
DC3_FAULT
0
DCDC3 fault mask for the
/VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
1
DC2_FAULT
DCDC2 fault mask for the
/VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
0
DC1_FAULT
DCDC1 fault mask for the
/VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
Table 81 DC Converter /VCCFAULT Mask Bits
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14.7 CONFIGURING THE LDO REGULATORS
The configuration of the LDO Regulators is described in the following sections. Some of the control
fields form part of the Custom Mode configuration settings and therefore will not require to be set in
software in some applications.
14.7.1
LDO REGULATOR ENABLE
The LDO Regulators can be enabled in software using the register fields defined in Table 82. To
reduce supply in-rush current, individual regulators should be programmed to start in different time
slots within the start-up sequence.
In the WM8351 ACTIVE state, the LDO Regulators can be enabled in software using the LDOn_ENA
bits. Setting these bits whilst in the Pre-Active state (see Figure 65) will not immediately enable the
corresponding LDO Regulators; these bits will only become effective once the WM8351 has reached
the ACTIVE state.
Each Regulator may be programmed to switch on in a selected timeslot within the start-up sequence.
The WM8351 will set the LDOn_ENA field for any LDO Regulator that is enabled during the start-up
sequence. Note that setting the LDOn_ENSLOT fields in software is only relevant to the
Development Mode, as these fields are assigned preset values in each of the Custom Modes.
Each Regulator may be programmed to switch off in a selected timeslot within the shutdown
sequence. If a Regulator is not allocated to one of the 14 shutdown timeslots, it will be disabled when
the WM8351 enters the OFF state.
ADDRESS
R13 (0Dh) or
BIT
DEFAULT
DESCRIPTION
8
LDO1_ENA
LABEL
0
LDO1 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on see DCDC/LDO Status register for actual
converter status.
9
LDO2_ENA
0
LDO2 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on see DCDC/LDO Status register for actual
converter status.
10
LDO3_ENA
0
LDO3 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on see DCDC/LDO Status register for actual
converter status.
11
LDO4_ENA
0
LDO4 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on see DCDC/LDO Status register for actual
converter status.
R176 (B0h)
DC-DC / LDO
requested
Note: These bits can be accessed through R13 or through R176. Reading from or writing to either
register location has the same effect.
R201 (C9h)
for LDO1
R204 (CCh)
for LDO2
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13:10
LDOn_ENSL
OT [3:0]
0000
Time slot for LDOn start-up
0000 = Disabled (do not start up)
0001 = Start-up in time slot 1
… (total 14 slots available)
1110 = Start-up in time slot 14
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ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
1111 = Start up on entering ACTIVE
R207 (CFh)
for LDO3
9:6
LDOn_SDSL
OT [3:0]
0000
R210 (D2h)
for LDO4
Time slot for LDOn shutdown.
0000 = Shut down on entering OFF
0001 = Shutdown in time slot 1
…. (total 14 slots available)
1110 = Shutdown in time slot 14
1111 = Shut down on entering OFF
Note: n is a number between 1 and 4 that identifies the individual LDO regulator
Table 82 Enabling and Disabling the LDO Regulators
14.7.2
LDO REGULATOR CONTROL
The LDO Regulators can be configured to operate in different modes using the register bits
described in Table 83.
In Switch mode, the Regulators operate as current-limited switches with no voltage regulation.
In LDO Regulator mode, the Regulators generate an output voltage determined by the LDOn_VSEL
fields. The LDO Regulators are dynamically programmable - the output voltage may be adjusted in
software at any time. The Regulators are critically damped to ensure there is no voltage overshoot or
undershoot when adjusting the output voltage.
The default output voltage for the LDO Regulators is set by writing to the LDOn_VSEL register bits.
The ‘image’ voltage settings LDOn_VIMG are alternate values that may be invoked when the
HIBERNATE software or hardware control is asserted.
ADDRESS
R200 (C8h)
for LDO1
R203 (CBh)
for LDO2
BIT
LABEL
14
LDOn_SWI
4:0
LDOn_VSEL
[4:0]
R206 (CEh)
for LDO3
DEFAULT
LDOn Regulator mode
0 = LDO voltage regulator
1 = Current-limited switch (no voltage
regulation, LDOn_VSEL has no
effect)
Dependant on
CONFIG[1:0]
settings
LDOn Regulator output voltage (when
LDOn_SWI=0)
1 1111 = 3.3V
… (100mV steps)
1 0000 = 1.8V
0 1111 = 1.65V
… (50mV steps)
0 0000 = 0.9V
R209 (D1h)
for LDO4
R202 (CAh)
for LDO1
DESCRIPTION
0
4:0
LDOn_VIMG
[4:0]
1 1100
R205 (CDh)
for LDO2
R208 (D0h)
for LDO3
LDOn Regulator output image voltage
1 1111 = 3.3V
… (100mV steps)
1 0000 = 1.8V
0 1111 = 1.65V
… (50mV steps)
0 0000 = 0.9V
R211 (D3h)
for LDO4
Note: n is a number between 1 and 4 that identifies the individual LDO regulator
Table 83 Controlling Regulator Voltage and Switch Mode
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The LDO Regulators can also be controlled by the device HIBERNATE bit, or by hardware input
signals L_PWR1, L_PWR2 and L_PWR3. Several GPIO pins can be assigned as L_PWR pins. Each
Regulator can be assigned to one of these three signals, or else to the device HIBERNATE bit. The
signals are active high and each Regulator’s response to the selected signal is programmable as
defined in Table 84.
Note that, when a GPIO pin is configured as a Hibernate input pin, and this input is asserted, then all
LDO Regulators will be placed in Hibernate mode.
In order to use GPIO pins as L_PWR pins, they must be configured by setting the respective
GPn_FN, and GPn_DIR bits to the appropriate value (see Section 20).
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
Note: n is a number between 1 and 4 that identifies the individual LDO regulator
R202 (CAh)
for LDO1
13:12
LDOn_HIB_M
ODE [1:0]
00
LDO Hibernate behaviour:
00 = Select voltage image settings
01 = disable output
10 = reserved
11 = reserved
9:8
LDOn_HIB_T
RIG [1:0]
00
LDO Hibernate signal select
00 = Hibernate register bit
01 = L_PWR1
10 = L_PWR2
11 = L_PWR3
R205 (CDh)
for LDO2
R208 (D0h)
for LDO3
R211 (D3h)
for LDO4
Table 84 Configuring Hardware Control for LDO Regulators
When the LDO Regulators are disabled, the output can be set to float or else the outputs can be
actively discharged through internal resistors. This feature is controlled using the register bits
described in Table 85.
Note that the “float” option is only supported when at least one other LDO Regulator remains
enabled. If LDO Regulators 1, 2, 3 and 4 are all disabled, then the LDO Regulator outputs will be
discharged, regardless of the LDOn_OPFLT registers.
ADDRESS
R200 (C8h)
for LDO1
BIT
10
LABEL
LDOn_OPFLT
DEFAULT
DESCRIPTION
0
Enable discharge of LDOn outputs
when LDOn disabled
0 = Enabled - Output to be discharged
1 = Disabled - Output is left floating
Note - if LDO Regulators 1, 2, 3 and 4
are all disabled, then the outputs will all
be discharged, regardless of the
LDOn_OPFLT bit.
R203 (CBh)
for LDO2
R206 (CEh)
for LDO3
R209 (D1h)
for LDO4
Note: n is a number between 1 and 4 that identifies the individual LDO regulator
Table 85 Output Float Control for LDO Regulators
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14.7.3
INTERRUPTS AND FAULT PROTECTION
Each LDO Regulator is monitored for voltage accuracy and fault conditions. An undervoltage
condition is set if the voltage falls below 95% of the required level. The action taken in response to a
fault condition can be set independently for each LDO Regulator, as described in Table 86. The
LDOn_ERRACT fields configure the fault response to disable the respective regulator or to shut
down the entire system if desired. In addition, LDO Regulator fault conditions also generate a
second-level interrupt (see Section 24).
To prevent false alarms during short current surges, faults are only signalled if the fault condition
persists.
ADDRESS
R201 (C9h)
for LDO1
BIT
LABEL
DEFAULT
15:14
LDOn_ERRACT
[1:0]
00
R204 (CCh)
for LDO2
DESCRIPTION
Action to take on fault (as well as
generating an interrupt):
00 = ignore
01 = shut down regulator
10 = shut down system
11 = reserved (shut down system)
R207 (CFh)
for LDO3
R210 (D2h)
for LDO4
Note: n is a number between 1 and 4 that identifies the individual LDO regulator
Table 86 Fault Responses for LDO Regulators
The DC-DC Converters and the LDO Regulators have a first-level interrupt, UV_INT (see
Section 24). This comprises second-level interrupts from each of the DC-DC Converters and the
LDO Regulators.
Each LDO Regulator has a dedicated second-level interrupt which indicates an under-voltage
condition. These can be masked by setting the applicable mask bit as defined in Table 87.
ADDRESS
BIT
R28 (1Ch)
Under Voltage
Interrupt Status
11
UV_LDO4_EINT
LDO4 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
10
UV_LDO3_EINT
LDO3 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
9
UV_LDO2_EINT
LDO2 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
8
UV_LDO1_EINT
LDO1 Under-voltage interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
“IM_” + name of respective
bit in R28
Mask bits for LDO regulator under-voltage
interrupts
Each of these bits masks the respective
bit in R28 when it is set to 1 (e.g.
UV_LDO1_EINT in R28 does not trigger a
UV_INT interrupt when
IM_UV_LDO1_EINT in R36 is set).
R36 (24h)
Under Voltage
Interrupt Mask
as in
R28
LABEL
DESCRIPTION
Table 87 LDO Regulator Interrupts
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The status of the LDO Regulators can be indicated and monitored externally via a GPIO pin
configured as /VCC_FAULT (see Section 20). When a GPIO pin is configured as /VCC_FAULT
output, a logic low level on this pin indicates that there is a fault condition on one of the LDO
Regulators, DC-DC Converters, or the Current Limit switch.
The /VCC_FAULT output is configurable by the control fields in Register R215. The fields described
in Table 88 determine which of the LDOs contribute to the /VCC_FAULT indication. An undervoltage
or overvoltage condition on any unmasked LDO will cause the /VCC_FAULT output to be set to logic
low.
ADDRESS
R215 (D7h)
VCC_FAULT
BIT
LABEL
DEFAULT
DESCRIPTION
11
LDO4_FAULT
0
LDO4 fault mask for the /VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
10
LDO3_FAULT
0
LDO3 fault mask for the /VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
9
LDO2_FAULT
0
LDO2 fault mask for the /VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
8
LDO1_FAULT
0
LDO1 fault mask for the /VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
Table 88 LDO Regulator /VCCFAULT mask bits
14.7.4
ADDITIONAL CONTROL FOR LDO1
By default, all DC Converters and LDOs are disabled in the OFF state. Additional control is provided
to enable LDO1 to be configured differently, allowing it to be enabled in the OFF state, or else to be
controlled by a GPIO pin configured as /LDO_ENA (see Section 20.2.2). These options are selected
by setting the register fields described in Table 89. In practical applications, however, these options
are set by the Config Mode settings and are not set by users.
Operation of LDO1 in the OFF state is subject to the restriction that VOUT1 must be set to at least
1.8V.
CONDITION
DESCRIPTION
LDO1_PIN_MODE = 0
LDO1 controlled as normal via register bits
LDO1_PIN_MODE = 1
LDO1_PIN_EN = 0
LDO1 enabled at all times
LDO1_PIN_MODE = 1
LDO1_PIN_EN = 1
LDO1 controlled by /LDO_ENA only
Table 89 LDO1 Additional Control
Notes:
w
1.
LDO1 is always disabled in BACKUP and ZERO states.
2.
When LDO1_PIN_MODE = 1, then LDO1 only operates as determined by the LDO1_VSEL
field. The Hibernate settings are ignored under this configuration.
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14.8 DC-DC CONVERTER OPERATION
14.8.1
OVERVIEW
The WM8351 provides four DC-DC switching converters. Three of these are Buck (Step-down)
converters and one is a Boost (Step-up) converter. The principal characteristics and typical usage for
each DC-DC converter are shown below.
Typical Application
Converter Type
DC-DC 1
DC-DC 2
DC-DC 3 / 4
Other system
components
Constant-current LED
drivers or I/O supply
Digital supply for
WM8351 and other
components
Step-down
Step-up,
using external NFET
Step-down
Input Voltage Range
2.7V to 5.5V
Output Voltage Range
0.85V to 3.4V
Load Current Rating
Up to 1A
(may be limited
by application)
Switching Frequency
2.0MHz
5V to 20V
170mA @ 5V
40mA @ 20V
1.0MHz
0.85V to 3.4V
Up to 500mA
(may be limited by
application)
2.0MHz
Table 90 DC-DC Converter Characteristics
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14.8.2
DC-DC STEP DOWN CONVERTERS
DC-DC Converters 1, 3 and 4 are versatile step-down, pulse-width-modulated (PWM) DC-DC
converters designed to deliver high power efficiency across full load conditions. The converters offer
Active and Standby/Hysteretic operating modes in order to maximise efficiency for different loads. A
low-power LDO sleep mode is also available to further reduce quiescent current at very lightly loaded
conditions. The DC-DC Converters maintain output voltage regulation during the switch-over between
operating modes.
The step-down regulators are designed with fixed frequency current mode architecture. The current
feedback loop is through the PMOS current path and is amplified and summed with an internal slope
compensation network. The voltage feedback loop is through an internal feedback divider. The ON
time is determined by comparing the summed current feedback and the output of the switcher error
amplifier. The period is set by the internal RC oscillator, which provides a 2.0MHz clock.
A supply pin (PVDD) provides the core supply for DC-DC Converter 3. Another supply pin
(LINEDCDC) provides the core supply for DC-DC Converters 1 and 4. The input voltage connection
to DC-DC Converters 1, 3 and 4 is provided on PV1, PV3 and PV4 respectively. These input voltages
may be provided from the LINE voltage.
The connections to DC-DC Converter 1 are illustrated in Figure 69. The equivalent circuit applies to
DC-DC Converters 3 and 4 also.
Figure 69 Step-Down DC-DC Converter Connections
The external components at the converter output are required by the DC-DC Converter integral loop
compensation circuit. Note that the recommended output capacitor Cout varies according to the
required transient response on DC-DC1. A single recommended value is provided for Cout on DCDC3 and DC-DC4.
See Section 29.3 for details of the recommended external components.
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14.8.3
DC-DC STEP UP CONVERTER
DC-DC Converter 2 is a versatile step-up pulse-width-modulated (PWM) DC-DC converter designed
to deliver high power efficiency across full load conditions. The converter can also be used as a
switch.
DC-DC Converter 2 is designed with a fixed frequency current mode architecture. The clock
frequency is set by the internal RC oscillator, which provides a 1.0MHz clock.
The PVDD supply pin provides the core supply for DC-DC Converter 2.
The connections to DC-DC Converter 2 in Constant Voltage Mode are illustrated in Figure 70. See
Section 29.4 for details of the connections for the Constant Current and USB operating modes of the
DC-DC Step-Up Converter.
Figure 70 Step-Up DC-DC Converter Connections
The external components at the converter output are required by the DC-DC Converter integral loop
compensation circuit. Note that the recommended output capacitor Cout varies according to the
required output voltage.
See Section 29.4 for details of the recommended external components.
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14.9 LDO REGULATOR OPERATION
The WM8351 provides four identical LDO voltage regulators to generate accurate, low-noise supply
voltages for various system components. The LDOs can also operate as current-limited switches,
with no voltage regulation; this is useful for ‘Hot Swap’ outputs, i.e. supply rails for external devices
that are plugged in when the system is already powered up - the current-limiting function prevents the
in-rush current into the external device from disturbing other system power supplies.
The LDO regulators are dynamically programmable. Each regulator output is current-limited; the
output voltage is automatically throttled back if the load current exceeds the limit.
A single supply pin (LDOVDD) provides the core supply for all four LDOs. The input voltage
connection to LDO1 and LDO2 is provided on the VINA pin. The input voltage connection to LDO3
and LDO4 is provided on the VINB pin. These input voltages can be provided from one of the DC-DC
Converters or from the LINE voltage.
Note that separate voltage regulators are provided to generate the backup supply VRTC and the
microphone bias voltage MICBIAS.
The connections to LDO Regulator 1 are illustrated in Figure 71. The equivalent circuit applies to
LDO2, LDO3 and LDO4.
Figure 71 LDO Regulator Connections
An input and output capacitor are recommended for each LDO Regulator, as illustrated above. See
Section 29.5 for details of the recommended external components.
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15 CURRENT LIMIT SWITCH
15.1 GENERAL DESCRIPTION
The WM8351 includes an on-chip Current Limit Switch to control external devices and to support hotplugging of accessories and power supplies.
When the switch is enabled, it normally has a low resistance, allowing current to pass through (from
the IP pin to the OP pin). If the current limit threshold is reached, the WM8351 can raise an interrupt,
disable the switch and/or shut down the whole device.
15.2 CONFIGURING THE CURRENT LIMIT SWITCH
15.2.1
CURRENT LIMIT SWITCH ENABLE
The Current Limit Switch can be enabled in software using the register fields defined in Table 91.
In Active mode, the Current Limit Switch can be enabled in software using the LS_ENA bit. Setting
this bit whilst in the Pre-Active state (see Figure 65) will not immediately enable the Current Limit
Switch; this bit will only become effective once the WM8351 has reached the Active state.
The Current Limit Switch may be programmed to become enabled in a selected timeslot within the
start-up sequence. When this happens, the WM8351 will set the LS_ENA bit. Note that setting the
LS_ENSLOT field in software is only relevant to the Development Mode, as this field is assigned a
preset value in each of the Custom Modes.
The Current Limit Switch may be programmed to switch off in a selected timeslot within the shutdown
sequence. If the Limit Switch is not allocated to one of the 14 shutdown timeslots, it will be disabled
when the WM8351 enters the OFF state.
The Current Limit Switch behaviour in Hibernate mode is controlled by the LS_HIB_MODE bit.
ADDRESS
BIT
R13 (0Dh)
15
R176 (B0h)
DC-DC / LDO
requested
15
LABEL
LS_ENA
DEFAULT
DESCRIPTION
0
Limit switch enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on - see
DCDC/LDO Status register for actual
converter status.
Note: LS_ENA can be accessed through R13 or through R176. Reading from or writing to either
register location has the same effect.
R199 (C7h)
Limit switch
control
13:10
LS_ENSLOT
[3:0]
0000
Time slot for Limit Switch start-up
0000 = Disabled (do not start up)
0001 = Start-up in time slot 1
… (total 14 slots available)
1110 = Start-up in time slot 14
1111 = Start-up on entering ACTIVE
9:6
LS_SDSLOT
[3:0]
0000
Time slot for Limit Switch shutdown.
0000 = Shut down on entering OFF
0001 = Shutdown in time slot 1
…. (total 14 slots available)
1110 = Shutdown in time slot 14
1111 = Shut down on entering OFF
4
LS_HIB_MO
DE
0
Limit switch hibernate mode setting
0 = disabled
1 = leave setting as in Active mode
Table 91 Enabling and Disabling the Current Limit Switch
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15.2.2
CURRENT LIMIT SWITCH BULK DETECTION CONTROL
The Current Limit Switch can be connected to voltages which may be higher than the device LINE
voltage. To support this capability, the switch is powered from the highest available voltage; this
requires a bulk detection circuit in order to select the highest available voltage. The bulk detection
circuit is always enabled whenever the Current Limit Switch is enabled.
It is possible to control whether the bulk detection circuit is enabled or not when the Current Limit
Switch is disabled. This is controlled in Active mode by the LS_PROT bit, and in Hibernate mode by
the LS_HIB_PROT bit.
Disabling the Bulk Detection circuit will reduce power consumption. It is important to note, however,
that the Bulk Detection circuit should always be enabled if voltages greater than LINE could be
present on IP or OP. This applies regardless of whether the Current Switch is open or closed.
ADDRESS
R199 (C7h)
Limit switch
control
BIT
LABEL
DEFAULT
1
LS_HIB_PRO
T
1
Controls the bulk detection circuit when
Limit Switch is disabled in Hibernate
mode.
0 = bulk detection disabled
1 = bulk detection enabled
DESCRIPTION
0
LS_PROT
1
Controls the bulk detection circuit when
Limit Switch is disabled in Active mode.
0 = bulk detection disabled
1 = bulk detection enabled
Table 92 Current Limit Switch Bulk Detection Control
15.2.3
INTERRUPTS AND FAULT PROTECTION
The response to an over-current condition is selectable. To prevent false alarms during short current
surges, faults are only signalled if the fault condition persists.
ADDRESS
R199 (C7h)
Limit switch
control
BIT
15:14
LABEL
LS_ERRACT
[1:0]
DEFAULT
00
DESCRIPTION
Current limit detection behaviour
00 = ignore
01 = disable switch
10 = shut down system
11 = shut down system
Table 93 Fault Response for the Current Limit Switch
The limit switch has its own first-level interrupt, OC_INT (see Section 24). This contains a single
second-level interrupt, OC_LS_EINT, indicating an over-current condition. OC_LS_EINT can be
masked by setting the IM_OC_LS_EINT bit.
ADDRESS
BIT
R29 (1Dh)
Over Current
Interrupt Status
15
OC_LS_EINT
LABEL
Limit Switch Over-current interrupt.
(Rising Edge triggered)
Note: This bit is cleared once read.
DESCRIPTION
R37 (25h)
Over Current
Interrupt Mask
15
IM_OC_LS_EINT
Mask bit for Limit switch over-current
interrupt
When set to 1, IM_OC_LS_EINT masks
OC_LS_EINT in R29 and does not trigger
an OC_INT interrupt when OC_LS_EINT is
set).
Table 94 Current Limit Switch Interrupts
The status of the Current Limit Switch can be indicated and monitored externally via a GPIO pin
configured as /VCC_FAULT (see Section 20). When a GPIO pin is configured as /VCC_FAULT
output, a logic low level on this pin indicates that there is a fault condition on one of the LDO
Regulators, DC-DC Converters, or the Current Limit switch.
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The /VCC_FAULT output is configurable by the control fields in Register R215. The LS_FAULT bit
described in Table 95 selects whether the Limit Switch contributes to the /VCC_FAULT indication.
When LS_FAULT = 0, then an overcurrent condition on the Limit Switch will cause the /VCC_FAULT
output to be set to logic low.
ADDRESS
R215 (D7h)
VCC_FAULT
BIT
15
LABEL
LS_FAULT
DEFAULT
0
DESCRIPTION
Limit Switch fault mask for the
/VCC_FAULT
0 = don't mask converter fault
1 = mask converter fault
Table 95 Limit Switch /VCCFAULT Mask
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16 CURRENT SINKS (LED DRIVERS)
16.1 GENERAL DESCRIPTION
The WM8351 includes four pins for driving different types of LEDs.
The ISINKA pin provides a programmable constant-current sink designed to drive a string of serially
connected LEDs, including white LEDs used in display backlights or in camera flash applications.
Using ISINKA in conjunction with DC-DC Converter 2 provides a particularly power-efficient way to
drive such LED strings. The ground connection associated with this Current Sink is the SINKGND
pin.
ISINKC, ISINKD and ISINKE are regular open-drain outputs. They are alternate functions of the
GPIO10, GPIO11 and GPIO12 pins respectively. These GPIOs are provided on the LINE power
domain; the associated ground connection is the GND pin.
16.2 CONSTANT-CURRENT SINK
ISINKA is a dedicated LED driver pin equipped with a programmable constant current sink. It is
designed to drive a string of serially connected white LEDs such as those used in display backlights
or photo-flash applications. Powering LEDs in this way is particularly power efficient because no
series resistor is required. DC-DC converter 2, operating as a current-controlled voltage source, is an
ideal power source for LED strings. This converter can generate voltages higher than BATT or LINE,
which can overcome the combined forward voltages of long LED strings (e.g. a string of 7 white
LEDs with a forward voltage of 4V requires at least 28V).
16.2.1
ENABLING THE SINK CURRENT
In Active mode, ISINKA can be enabled in software using the CS1_ENA register field defined in
Table 96. If required, the Current Sink function may also be controlled by the Hibernate bit.
Note that these control bits do not exist for ISINKC, ISINKD or ISINKE.
ADDRESS
BIT
R14 (0Eh)
Power mgmt
(7)
0
R172 (ACh)
Current Sink
Driver A
15
12
LABEL
DEFAULT
DESCRIPTION
CS1_ENA
0
Current Sink 1 enable (ISINKA pin)
0 = disabled
1 = enabled
CS1_HIB_MO
DE
0
Current Sink 1 behaviour in Hibernate
mode
0 = disable current sink in Hibernate
1 = leave current sink as in Active
Note: CS1_ENA can be accessed through R14 or through R172. Reading from or writing to either
register location has the same effect.
Table 96 Enabling ISINKA
When ISINKA is used in conjunction with DC-DC Converter 2, the ISINK should always be switched
on before the DC-DC Converter is switched on. Conversely, the DC-DC Converter should always be
switched off before the ISINK is switched off. If high voltages are used, additional external
components may also be needed to protect the WM8351.
16.2.2
PROGRAMMING THE SINK CURRENT
The sink current for ISINKA can be programmed by writing to the CS1_ISEL register bit. The current
steps are logarithmic to match the logarithmic light sensitivity characteristic of the human eye. The
step size is 1.5dB (i.e. the current doubles every four steps).
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ADDRESS
R172 (ACh)
Current Sink
Driver A
BIT
5:0
LABEL
CS1_ISEL
DEFAULT
DESCRIPTION
00 0000
ISINKA current = 4.05μA × 2CS1_ISEL/4
where CS1_ISEL is an unsigned binary
number
Minimum: 00 0000 = 4.05μA,
Maximum: 11 1111 = 220mA
(from circuit simulation)
or
CS1_ISEL = 13.3 × log (desired current /
4.05μA)
Table 97 Controlling the Sink Current for ISINKA
Note that currents above 40mA are not supported continuously; these settings are intended for flash
mode only.
16.2.3
FLASH MODE
The current sink can either sink current continuously (LED mode) or in short bursts (flash mode). The
operating mode is selected by the CS1_FLASH_MODE bit, as described in Table 98.
In LED mode, the current sink is controlled by setting CS1_DRIVE. For as long as this bit is
asserted, the LED is enabled continuously.
In Flash mode, the current sink may be set to automatically flash every 4 seconds by setting
CS1_FLASH_RATE = 1, or may be triggered normally by setting CS1_FLASH_RATE = 0.
When normal triggering is selected in Flash mode, the trigger control can be either a GPIO Flash
input (see Section 20) or a register control. Setting CS1_TRIGSRC = 1 selects GPIO as the trigger.
The flash will be edge triggered by the selected GPIO input. Setting CS1_TRIGSRC = 0 selects the
register field CS1_DRIVE as the trigger. In this case, writing a 1 to CS1_DRIVE will trigger a flash;
this bit will be reset at the end of the flash.
In all flash modes, the duration of each flash is set by CS1_FLASH_DUR. The status of each current
sink may be read from the CS1_DRIVE bit.
In all modes, the current sink must also be enabled via the applicable CS1_ENA bit (see Table 96).
Note that some photo-flash applications may require a reservoir capacitor to store sufficient charge
for the flash.
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ADDRESS
R173 (ADh)
CSA Flash
Control
BIT
LABEL
DEFAULT
15
CS1_FLASH_M
ODE
0
Determines the function of the current
sink
0 = LED mode
1 = Flash mode
DESCRIPTION
14
CS1_TRIGSRC
0
Selects the trigger in Flash mode.
0 = Flash triggered by CS1_DRIVE bit
1 = Flash triggered from GPIO pin
configured as FLASH
This bit has no effect when
CS1_FLASH_MODE=0
13
CS1_DRIVE
0
Enables the current sink ISINKA
LED mode0 = disable LED
1 = enabled LED
FLASH modeRegister bit used to trigger the flash, if
CS1_TRIGSRC is set to 0. Flash is
started when the bit goes high, it is then
reset at the end of the flash duration.
Duration is determined by
CS1_FLASH_DUR. This bit has no effect
if CS1_TRIGSRC is set to 1.
12
CS1_FLASH_R
ATE
0
Determines the Flash rate
0 = Normal Operation. Once per trigger
(Either register bit or GPIO)
1 = Flash will be internally triggered
every 4 second
9:8
CS1_FLASH_D
UR [1:0]
00
Sets duration of flash
00 = 32ms
01 = 64ms
10 = 96ms
11 = 1024ms
Table 98 Configuring Flash Mode for ISINKA
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16.2.4
ON/OFF RAMP TIMING
The sink current for ISINKA can be programmed to switch on and off gradually in LED and in Flash
modes. The current ramp duration is as described in Table 99.
ADDRESS
R173 (ADh)
CSA Flash
Contro
BIT
LABEL
DEFAULT
5:4
CS1_OFF_RA
MP [1:0]
00
1:0
CS1_ON_RAM
P [1:0]
00
DESCRIPTION
Switch-off ramp duration
LED Mode
Flash Mode
00 = instant (no
ramp)
01 = 0.25s
10 = 0.5s
11 = 1s
00 = instant (no
ramp)
01 = 1.95ms
10 = 3.91ms
11 = 7.8ms
Switch-on ramp duration
Similar to CS1_OFF_RAMP
Table 99 Configuring On/Off Ramp Timing for ISINKA
16.2.5
INTERRUPTS AND FAULT PROTECTION
The Current Sink has its own first-level interrupt, CS_INT (see Section 24). This contains a single
second-level interrupt, CS1_EINT, indicating that the Current Sink is unable to sink the amount of
current that has been programmed and may be out of spec. CS1_EINT can be masked by setting the
IM_CS1_EINT bit.
ADDRESS
BIT
R26 (1Ah)
Interrupt Status
2
13
CS1_EINT
LABEL
Flag to indicate drain voltage can no
longer be regulated and output current
may be out of spec.
(Rising Edge triggered)
Note: This bit is cleared once read.
DESCRIPTION
R34 (22h)
Interrupt Status
2 Mask
13
IM_CS1_EINT
Mask bit for Current Sink over-current
interrupt
When set to 1, IM_CS1_EINT masks
CS1_EINT in R26 and does not trigger a
CS_INT interrupt when CS1_EINT is set.
Table 100 Current Sink Interrupts
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16.3 OPEN-DRAIN LED OUTPUTS
The three open-drain outputs ISINKC, ISINKD and ISINKE are alternate functions of the GPIO10,
GPIO11 and GPIO12 pins, respectively (see Section 20). They can drive LEDs connected to LINE,
with a series resistor. Note that the GPIO pins have other alternate functions, which will not be
available that pin is configured as ISINKC, ISINKD or ISINKE.
16.4 LED DRIVER CONNECTIONS
The recommended connection for LEDs on ISINKA is illustrated in Figure 72.
Figure 72 LED Connection to ISINKA
The recommended connections for LEDs on ISINKC, ISINKD and ISINKE are illustrated in Figure 73.
Figure 73 LED Connections to ISINKC, ISINKD and ISINKE
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17 POWER SUPPLY CONTROL
17.1 GENERAL DESCRIPTION
The WM8351 can take its power supply from a Wall adaptor, a USB interface or from a single-cell
lithium battery. The WM8351 autonomously chooses the most appropriate power source available,
and supports hot-swapping between sources (ie. the system can remain in operation while different
sources are connected and disconnected).
Comparators within the WM8351 identify which power supplies are available and select the power
source in the following order of preference:
•
Wall adaptor (LINE pins)
•
USB power rail (USB pins)
•
Battery (BATT pins)
Note that the Wall supply is always the first choice of supply, (providing that it is within required
limits), even if the Wall supply voltage is lower than the USB voltage.
When Wall or USB is selected as the power source, this may be used to charge the Battery, using
the integrated battery charger circuit. For battery charging to occur, the USB or LINE supply voltage
must be no less than 4.0V.
Figure 74 illustrates the WM8351 connections associated with the WALL, USB and Battery supplies.
Figure 74 WM8351 Power Supply Connections
The Wall Adaptor supply connects to LINE via a FET switch as illustrated in Figure 74. The FET
switch is necessary in order to provide isolation between the Wall supply and the Battery/USB
supplies; this is vital in the event of the USB voltage being greater than the Wall supply voltage.
The Wall Adapter voltage is sensed directly on the WALL_FB pin; this allows the WM8351 to
determine the preferred supply, including when the FET is switched off.
The gate connection to the external FET is controlled by LINE_SW, which is an alternate function
that can be enabled on GPIO12 (see Section 20). Note that, if the USB connection is not used, then
the FET may not be required and the Wall supply may be connected directly to LINE.
LINE is primarily an output from the WM8351; this output is the preferred supply, where the WM8351
has arbitrated between the Wall, Battery and USB connections. This output is suitable for supplying
power to the other blocks of the WM8351, including the DC-DC Converters and LDO Regulators.
LINE is also an input under some conditions, such as battery charging from Wall or providing power
at the USB connection.
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HIVDD is an external connection which exists for the purposes of decoupling only. It represents the
highest available power supply connected to the WM8351. It should be noted that the preferred
supply (on the LINE pin) is not necessarily the same voltage as HIVDD - the Wall supply will always
be the preferred voltage when it is within the intended limits, even if it is not also the highest available
source.
The main battery connects directly to the BATT pin. When the battery is the preferred supply source,
this pin is an input. When battery charging is in operation, this pin is an output. (Note that the backup
VRTC battery is connected separately - see Section 17.5.)
The USB interface connects directly to the USB pin. In USB Master Mode (USB is less than LINE),
the WM8351 can supply power to external devices on this pin. In USB Slave Mode (USB is greater
than LINE), the WM8351 can use this pin as an input to power the device and/or to charge a battery
connected to the BATT pin. Note that, when USB is the preferred power supply, the Battery may also
be used if necessary to supplement the current drawn from the USB pin (ie. to source current into
LINE when required).
All loads connected to the WM8351 should normally be connected to the LINE pin. The inputs to the
DC-DC Converters and LDOs should be connected to the LINE pin. It is not recommended to
connect any load directly to the battery (BATT).
Note that the inputs to the LDOs may be connected to the outputs of the DC-DCs if desired.
17.2 BATTERY POWERED OPERATION
The WM8351 selects battery power when the Battery voltage is higher than the Wall (LINE) and USB
supplies. In practical usage, this means the Battery is used when Wall (LINE) and USB are both
disconnected.
The battery can also be used to supplement the USB supply when required (ie. to source current into
LINE).
If the Wall (LINE) or USB supply becomes available during battery operation, then the selected
power source is adjusted accordingly.
Battery pack temperature sensing is enabled by default. The battery’s NTC resistor is monitored via
the AUX1 pin on the WM8351, as described in Section 17.7. Note that the absence of this NTC
connection will lead to a temperature failure condition being detected and battery charging will not be
possible.
Safe operation of the battery charger outside the designed operating temperatures is not guaranteed
when a battery NTC resistor is not used. The designed operating temperatures are noted in
Section 17.7.7.
17.3 WALL ADAPTOR (LINE) POWERED OPERATION
The WM8351 selects Wall Adaptor power via the LINE pins whenever the Wall Adaptor supply is
within the normal operating limits of 4.0V to 5.5V. The Wall Adaptor is also selected as the power
source below 4.0V in the case where it is the highest available power source. The minimum LINE
voltage is a programmable threshold in the range 2.9V to 3.6V (see Section 18). The maximum
recommended operating voltage for LINE is 5.5V.
Note that USB power is not used when a suitable LINE supply is available, even if the USB supply is
higher than the Wall (LINE) supply.
If the Wall (LINE) supply becomes unsuitable and a USB is available, then the USB supply will be
selected as the preferred power source. Note that, when hot-swapping from Wall (LINE) to USB
supply, a usable Battery must be present on the BATT pin.
When the Wall (LINE) supply is selected and a Battery is connected, then trickle charging is enabled
by default, including when the WM8351 is in the OFF or HIBERNATE states. When the WM8351 is
in the ACTIVE state, then fast charging may be selected under software control.
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17.4 USB POWERED OPERATION
The WM8351 selects USB Slave mode by default. In USB Slave Mode, the USB pin can be used as
one of the sources of power for the WM8351. In USB Master Mode (selected using the USB_MSTR
register bit) the WM8351 can provide power to an external USB device.
In USB Slave mode, the WM8351 selects USB power if the Wall (LINE) supply is outside its normal
operating limits and the USB supply is the highest supply source available. For a transition from OFF
to ACTIVE state to occur under USB power, the USB supply must be no less than 4.0V.
The maximum current drawn from the USB supply can be set to 100mA (USB low power mode) or
500mA (USB high power mode). The default is set according to the selected Config Mode (see
Section 14).
When the WM8351 is in the ACTIVE state, USB high power mode can be selected using the register
bits USB_MSTR_500MA (in USB Master Mode) or USB_SLV_500MA (in USB Slave Mode) as
defined in Table 101. If a USB current higher than the applicable threshold is demanded, then
internal protection circuits will limit the USB current, and the USB_LIMIT_EINT interrupt will be
asserted.
Short term currents higher than 500mA can also be supported. This may be necessary for supporting
transient demands (eg. for a hard drive starting up). When the USB_NOLIM register field is set, the
internal protection circuits are disabled, and the current limit interrupt threshold is raised to double
the normal value. In 500mA mode, the current limit interrupt threshold is raised to approximately 1A.
This feature must be used with caution, as the internal protection circuits are disabled when
USB_NOLIM is set. The maximum steady-state current supported is 500mA; higher currents can
only be supported for short term transients.
USB power may be supplemented by battery power if available and if necessary to maintain the USB
current within the applicable limit. If a suitable Wall (LINE) supply becomes available during USB
operation, then this will be selected as the preferred power source. Note that, when hot-swapping
from USB to Wall supply, a usable Battery must be present on the BATT pin.
In USB low power mode, trickle charging is enabled by default. Trickle charging is suspended if
necessary to keep within the 100mA USB limit.
In USB high power mode, fast charging is possible (subject to other conditions - see Section 17.7.4).
The fast charge current is controlled dynamically as necessary to keep the overall USB current within
the 500mA limit.
Note that Battery Charging from the USB source is only possible in USB Slave Mode.
USB power may be suspended by writing to the USB_SUSPEND register bit. Setting this bit to ‘1’
disconnects the WM8351 from the USB supply, resulting in the selection of Battery as the power
source. USB Suspend mode is invoked under software control, by writing to the USB_SUSPEND bit.
Suspend mode should be invoked whenever the USB connection is not used.
To comply with the USB 2.0 specification, the host processor should initially invoke USB Suspend
mode after the WM8351 has successfully started up, and whenever the USB connection is not in
use. If the USB connection is active and USB enumeration has been completed, the host processor
may (but is not required to) switch the WM8351 into USB low-power mode or USB high-power mode.
However, if wall adaptor power is available, it is recommended to remain in USB Suspend mode.
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ADDRESS
BIT
R4 (04h)
System
Control 2
14
USB_SUSPEND
LABEL
DEFAULT
0
Opens the USB switch
0 = USB enabled
1 = USB suspended
The register bit defaults to 0, when a
reset happens or LINE < UVLO or the
system fail on boot due to the upper
limit of the Hysteresis Comp not been
met.
DESCRIPTION
13
USB_MSTR
0
Set the chip to be a USB master
0 = Slave
1 = Master
The register bit defaults to 0, when a
reset happens or the USB state
machine moves from MASTER mode to
SLAVE mode.
11
USB_MSTR_500MA
0
Set 500mA or 100mA mode when the
USB switch is in master mode
0 = 100mA
1 = 500mA
9
USB_SLV_500MA
Dependant
on
CONFIG
settings
Set 500mA or 100mA mode when the
USB switch is in slave mode
0 = 100mA
1 = 500mA
The register bit defaults to 0, when a
reset happens or LINE