Low Noise Stereo Codec with Enhanced
Recording and Playback Processing
ADAU1381
FEATURES
GENERAL DESCRIPTION
24-bit stereo audio ADC and DAC
400 mW speaker amplifier (into 8 Ω load)
Built-in sound engine for audio processing
Wind noise detection and autofiltering
Enhanced stereo capture (ESC)
Dual-band automatic level control (ALC)
6-band equalizer, including notch filter
Sampling rates from 8 kHz to 96 kHz
Stereo pseudo differential microphone input
Optional stereo digital microphone input pulse-density
modulation (PDM)
Stereo line output
PLL supporting a range of input clock rates
Analog and digital I/O 1.8 V to 3.3 V
Software control via SigmaStudio graphical user interface
Software-controllable, clickless mute
Software register and hardware pin standby mode
32-lead, 5 mm × 5 mm LFCSP or 30-ball, 6 × 5 bump WLCSP
The ADAU1381 is a low power, 24-bit stereo audio codec. The
low noise DAC and ADC support sample rates from 8 kHz to
96 kHz. Low current draw and power saving modes make the
ADAU1381 ideal for battery-powered audio applications.
A configurable sound engine provides enhanced record and
playback processing to improve overall audio quality.
The record path includes two digital stereo microphone inputs
and an analog stereo input path. The analog inputs can be
configured for either a pseudo differential or a single-ended
stereo source. A dedicated analog beep input signal can be
mixed into any output path. The ADAU1381 includes a stereo
line output and speaker driver, which makes the device capable of
supporting dynamic speakers.
The serial control bus supports the I2C® or SPI protocols, and
the serial audio bus is programmable for I2S, left-justified, rightjustified, or TDM mode. A programmable PLL supports flexible
clock generation for all standard rates and available master clocks
from 11 MHz to 20 MHz.
APPLICATIONS
Digital still cameras
Digital video cameras
AGND2
AVDD2
AGND1
AVDD1
DVDDOUT
DGND
IOVDD
CM
FUNCTIONAL BLOCK DIAGRAM
ADAU1381
REGULATOR
BEEP
PGA
SOUND ENGINE
LMIC/LMICN/
MICD1
PGA
LMICP
AOUTL
DECIMATION
FILTERS
LEFT
ADC
AOUTR
LEFT
DAC
WIND NOISE
OUTPUT
MIXER
NOTCH FILTER
EQUALIZER
RMIC/RMICN/
MICD2
PGA
RMICP
RIGHT
ADC
SPP
RIGHT
DAC
SPN
AUTOMATIC LEVEL
CONTROL
08313-001
SDA/COUT
SCL/CCLK
ADDR0/CDATA
DAC_SDATA/
GPIO0
LRCLK/GPIO3
ADDR1/CLATCH
I2C/SPI
CONTROL PORT
SERIAL DATA
INPUT/OUTPUT PORTS
BCLK/GPIO2
PLL
MCKI
MICROPHONE
BIAS
ADC_SDATA/
GPIO1
PDN
MICBIAS
DIGITAL VOLUME
CONTROL
Figure 1.
Rev. B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2009–2011 Analog Devices, Inc. All rights reserved.
ADAU1381
TABLE OF CONTENTS
Features .............................................................................................. 1
Input Signal Path ........................................................................ 30
Applications....................................................................................... 1
Analog-to-Digital Converters................................................... 31
General Description ......................................................................... 1
Digital Dual-Band Automatic Level Control (ALC) ............. 31
Functional Block Diagram .............................................................. 1
Playback Signal Path ...................................................................... 32
Revision History ............................................................................... 3
Output Signal Paths ................................................................... 32
Specifications..................................................................................... 4
Digital-to-Analog Converters................................................... 32
Record Side Performance Specifications................................... 4
Line Outputs ............................................................................... 32
Output Side Performance Specifications................................... 6
Speaker Output........................................................................... 32
Power Supply Specifications........................................................ 8
Control Ports................................................................................... 33
Typical Power Management Measurements ............................. 9
I2C Port ........................................................................................ 33
Digital Filters................................................................................. 9
SPI Port ........................................................................................ 36
Digital Input/Output Specifications......................................... 10
Memory and Register Access.................................................... 36
Digital Timing Specifications ................................................... 11
Serial Data Input/Output Ports .................................................... 38
Absolute Maximum Ratings.......................................................... 14
TDM Modes................................................................................ 38
Thermal Resistance .................................................................... 14
General-Purpose Input/Outputs .................................................. 40
ESD Caution................................................................................ 14
Sound Engine.................................................................................. 41
Pin Configuration and Function Descriptions........................... 15
Signal Processing........................................................................ 41
Typical Performance Characteristics ........................................... 17
Processing Flow .......................................................................... 41
System Block Diagrams ................................................................. 20
Programming.............................................................................. 41
Theory of Operation ...................................................................... 24
Parameter Memory .................................................................... 41
Startup, Initialization, and Power ................................................. 25
Applications Information .............................................................. 42
Power-Up Sequence ................................................................... 25
Power Supply Bypass Capacitors.............................................. 42
Clock Generation and Management........................................ 26
GSM Noise Filter ........................................................................ 42
Enabling Digital Power to Functional Subsystems ................ 26
Grounding ................................................................................... 42
Setting Up the Sound Engine.................................................... 26
Speaker Driver Supply Trace (AVDD2) .................................. 42
Power Reduction Modes............................................................ 26
Exposed Pad PCB Design ......................................................... 42
Power-Down Sequence.............................................................. 26
Control Register Map..................................................................... 43
Clocking and Sampling Rates ....................................................... 27
Clock Management, Internal Regulator, and PLL Control... 44
Core Clock................................................................................... 27
Record Path Configuration....................................................... 48
Sampling Rates............................................................................ 27
Serial Port Configuration .......................................................... 53
PLL ............................................................................................... 28
Audio Converter Configuration............................................... 58
Record Signal Path.......................................................................... 30
Playback Path Configuration.................................................... 63
Rev. B | Page 2 of 84
ADAU1381
Pad Configuration.......................................................................70
Outline Dimensions........................................................................84
Digital Subsystem Configuration..............................................77
Ordering Guide ...........................................................................84
REVISION HISTORY
1/11—Rev. A to Rev. B
Changes to Pin PDN Description in Table 10 .............................16
Changes to Power-Down Pin (PDN) Section..............................26
Changes to Table 23 ........................................................................36
3/10—Rev. 0 to Rev. A
Changes to Output Side Performance Specifications Section
Condition Statement.....................................................................6
Added Endnote 1 to Table 3.............................................................8
Changes to Figure 23 ......................................................................20
Changes to Figure 24 ......................................................................21
Changes to Figure 25 ......................................................................22
Changes to Figure 26 ......................................................................23
Changes to Table 27 ........................................................................43
Added Register 16434 (0x4032), Dejitter Control Section ........76
Changes to Ordering Guide...........................................................84
10/09—Revision 0: Initial Version
Rev. B | Page 3 of 84
ADAU1381
SPECIFICATIONS
Performance of all channels is identical, exclusive of the interchannel gain mismatch and interchannel phase deviation specifications.
Supply voltages AVDD = AVDD1 = AVDD2 = I/O supply = 3.3 V, digital supply = 1.5 V, unless otherwise noted; temperature = 25°C;
master clock (MCLK) = 12.288 MHz (fS = 48 kHz, 256 × fS mode); input sample rate = 48 kHz; measurement bandwidth = 20 Hz to 20 kHz;
word width = 24 bits; load capacitance (digital output) = 20 pF; load current (digital output) = 2 mA; high level input voltage = 0.7 × IOVDD;
and low level input voltage = 0.3 × IOVDD. All power management registers are set to their default states.
RECORD SIDE PERFORMANCE SPECIFICATIONS
Specifications guaranteed at 25°C (ambient).
Table 1.
Parameter
ANALOG-TO-DIGITAL CONVERTERS
ADC Resolution
Digital Attenuation Step
Digital Attenuation Range
INPUT RESISTANCE
Noninverting Inputs PGA
(LMICP, RMICP)
Inverting Inputs PGA (LMICN, RMICN)
Beep Input PGA
SINGLE-ENDED MICROPHONE INPUT
TO ADC PATH
Full-Scale Input Voltage (0 dB)
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Total Harmonic Distortion + Noise
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Test Conditions/Comments
Min
Typ
Max
Unit
All ADCs
24
0.375
95
Bits
dB
dB
All gain settings
500
kΩ
0 dB gain
6 dB gain
10 dB gain
14 dB gain
17 dB gain
20 dB gain
26 dB gain
32 dB gain
0 dB
6 dB
10 dB
14 dB
−23 dB
20 dB
26 dB
32 dB
62
32
22
14
10
8
5
4
20
9
6
3.5
50
2
2
2
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
kΩ
Scales linearly with AVDD
AVDD = 1.8 V
AVDD = 3.3 V
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
−3 dBFS
AVDD = 1.8 V
AVDD = 3.3 V
AVDD/3.3
0.55 (1.56)
1.0 (2.83)
V rms
V rms (V p-p)
V rms (V p-p)
96
99.2
92
96.5
dB
dB
dB
dB
−88
−90
dB
dB
96
100
92
97
dB
dB
dB
dB
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
Rev. B | Page 4 of 84
94
92
ADAU1381
Parameter
Left/Right Microphone PGA Gain
Range
Left/Right Microphone PGA Mute
Attenuation
Interchannel Gain Mismatch
Offset Error
Gain Error
Interchannel Isolation
Power Supply Rejection Ratio
DIFFERENTIAL MICROPHONE INPUT TO
ADC PATH
Full-Scale Input Voltage (0 dB)
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Total Harmonic Distortion + Noise
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Left/Right Microphone PGA Mute
Attenuation
Interchannel Gain Mismatch
Offset Error
Gain Error
Interchannel Isolation
Common-Mode Rejection Ratio
BEEP TO LINE OUTPUT PATH
Full-Scale Input Voltage (0 dB)
Total Harmonic Distortion + Noise
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Test Conditions/Comments
AVDD = 3.3 V
Min
0
AVDD = 3.3 V; mute set by Register
0x400E, Bit 1, and Register 0x400F, Bit 1
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V
CM capacitor = 10 μF
AVDD = 3.3 V, 100 mV p-p at 217 Hz
AVDD = 3.3 V, 100 mV p-p at 1 kHz
Scales linearly with AVDD
AVDD = 1.8 V
AVDD = 3.3 V
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
−3 dBFS
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 3.3 V; mute set by Register
0x400E, Bit 1, and Register 0x400F, Bit 1
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V, 100 mV rms, 1 kHz
AVDD = 3.3 V, 100 mV rms, 20 kHz
94
92
Typ
Max
32
Unit
dB
−98
dB
50
0.25
−1
−98
mdB
mV
%
dB
−55
−55
dB
dB
AVDD/3.3
0.55 (1.56)
1.0 (2.83)
V rms
V rms (V p-p)
V rms (V p-p)
96
99.2
92
96.5
dB
dB
dB
dB
−84
−85
dB
dB
96
100
92
97
−98
dB
dB
dB
dB
dB
50
0.25
−1
−85
−60
−45
mdB
mV
%
dB
dB
dB
Scales linearly with AVDD
AVDD = 1.8 V
AVDD = 3.3 V
−3 dBFS input, measured at AOUTL pin,
beep gain set to 0 dB
AVDD = 1.8 V
AVDD = 3.3 V
AVDD/3.3
0.55 (1.56)
1.0 (2.83)
V rms
V rms (V p-p)
V rms (V p-p)
−88
−88
dB
dB
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
99
105
96
102
dB
dB
dB
dB
Rev. B | Page 5 of 84
ADAU1381
Parameter
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Beep Input Mute Attenuation
Offset Error
Gain Error
Interchannel Gain Mismatch
Beep Input PGA Gain Range
Beep Playback Mixer Gain Range
Power Supply Rejection Ratio
MICROPHONE BIAS
Bias Voltage
0.65 × AVDD
0.90 × AVDD
Bias Current Source
Noise in the Signal Bandwidth
Test Conditions/Comments
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 3.3 V; mute set by
Register 0x4008, Bit 3
AVDD = 3.3 V
AVDD = 3.3 V
Min
AVDD = 3.3 V
AVDD = 3.3 V
CM capacitor = 10 μF
AVDD = 3.3 V, 100 mV p-p at 217 Hz
AVDD = 3.3 V, 100 mV p-p at 1 kHz
Microphone bias enabled
−23
−15
AVDD = 1.8 V, low bias
AVDD = 3.3 V, low bias
AVDD = 1.8 V, high bias
AVDD = 3.3 V, high bias
AVDD = 3.3 V, high bias, high
performance
AVDD = 3.3 V, 20 Hz to 20 kHz
High bias, high performance
High bias, low performance
Low bias, high performance
Low bias, low performance
AVDD = 1.8 V, 20 Hz to 20 kHz
High bias, high performance
High bias, low performance
Low bias, high performance
Low bias, low performance
Typ
Max
Unit
99
105
96
102
−90
dB
dB
dB
dB
dB
10
−0.3
30
mV
dB
mdB
dB
dB
+32
+6
−58
−72
dB
dB
1.17
2.145
1.62
2.97
V
V
V
V
mA
5
39
78
25
35
nV√Hz
nV√Hz
nV√Hz
nV√Hz
35
45
23
23
nV√Hz
nV√Hz
nV√Hz
nV√Hz
OUTPUT SIDE PERFORMANCE SPECIFICATIONS
Specifications guaranteed at 25°C (ambient). The output load for the speaker output path is an 8 Ω, 400 mW speaker.
Table 2.
Parameter
DIGITAL-TO-ANALOG CONVERTERS
DAC Resolution
Digital Attenuation Step
Digital Attenuation Range
DAC TO LINE OUTPUT PATH
Full-Scale Output Voltage (0 dB)
Line Output Mute Attenuation,
DAC to Mixer Path Muted
Line Output Mute Attenuation,
Line Output Muted
Test Conditions/Comments
Min
Typ
Max
Unit
All DACs
24
0.375
95
Bits
dB
dB
Scales linearly with AVDD
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 3.3 V; mute set by Register
0x401C, Bit 5, and Register 0x401E, Bit 6
AVDD = 3.3 V; mute set by Register
0x4025, Bit 1, and Register 0x4026, Bit 1
AVDD/3.3
0.55 (1.56)
1.0 (2.83)
−85
V rms
V rms (V p-p)
V rms (V p-p)
dB
−85
dB
Rev. B | Page 6 of 84
ADAU1381
Parameter
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Total Harmonic Distortion + Noise
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Power Supply Rejection Ratio
Gain Error
Interchannel Gain Mismatch
Offset Error
DAC TO SPEAKER OUTPUT PATH
Differential Full-Scale Output Voltage
(0 dB)
Total Harmonic Distortion + Noise
4 Ω Load
8 Ω Load
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Power Supply Rejection Ratio
Differential Offset Error
Mono Mixer Mute Attenuation,
DAC to Mixer Path Muted
BEEP TO SPEAKER OUTPUT PATH
Differential Full-Scale Output Voltage
(0 dB)
Test Conditions/Comments
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
−3 dBFS
AVDD = 1.8 V
AVDD = 3.3 V
Min
Typ
Unit
−88
−88
dB
dB
dB
dB
dB
dB
dB
99
103
97
100
dB
dB
dB
dB
−55
−63
−1
50
10
dB
dB
dB
mdB
mV
AVDD/1.65
V rms
AVDD = 1.8 V
AVDD = 3.3 V
1.1 (3.12)
2.0 (5.66)
V rms (V p-p)
V rms (V p-p)
AVDD = 1.8 V, PO = 50 mW
AVDD = 3.3 V, PO = 175 mW
AVDD = 1.8 V, PO = 50 mW
AVDD = 3.3 V, PO = 175 mW
AVDD = 3.3 V, PO = 330 mW
AVDD = 3.3 V, PO = 440 mW
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
−60
−60
−60
−60
−60
−16
dB
dB
dB
dB
dB
dB
100
105
98
103
dB
dB
dB
dB
94
92
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
CM capacitor = 10 μF
AVDD = 3.3 V, 100 mV p-p at 217 Hz
AVDD = 3.3 V, 100 mV p-p at 1 kHz
AVDD = 3.3 V
AVDD = 3.3 V
AVDD = 3.3 V
PO = output power
Scales linearly with AVDD
94
92
99
103
97
100
Max
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
CM capacitor = 10 μF
AVDD = 3.3 V,100 mV p-p at 217 Hz
AVDD = 3.3 V, 100 mV p-p at 1 kHz
AVDD = 3.3 V
Mute set by Register 0x401F, Bit 0
100
105
98
103
dB
dB
dB
dB
−55
−55
2
−90
dB
dB
mV
dB
PO = output power
Scales linearly with AVDD
AVDD/1.65
V rms
AVDD = 1.8 V
AVDD = 3.3 V
1.1 (3.12)
2.0 (5.66)
V rms (V p-p)
V rms (V p-p)
Rev. B | Page 7 of 84
ADAU1381
Parameter
Total Harmonic Distortion + Noise
Dynamic Range
With A-Weighted Filter (RMS)
No Filter (RMS)
Signal-to-Noise Ratio
With A-Weighted Filter (RMS)
No Filter (RMS)
Power Supply Rejection Ratio
Differential Offset Error
Mono Mixer Mute Attenuation,
Beep to Mixer Path Muted
REFERENCE (CM PIN)
Common-Mode Reference Output
Test Conditions/Comments
Min
Typ
Max
Unit
8 Ω, 1 nF load, AVDD = 1.8 V, PO = 50 mW
AVDD = 3.3 V, PO = 175 mW
−60 dB input
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
−60
−60
dB
dB
97
103
94
100
dB
dB
dB
dB
AVDD = 1.8 V
AVDD = 3.3 V
AVDD = 1.8 V
AVDD = 3.3 V
CM capacitor = 10 μF
100 mV p-p at 217 Hz
100 mV p-p at 1 kHz
98
103
96
101
dB
dB
dB
dB
−57
−60
2
−90
dB
dB
mV
dB
AVDD/2
V
Mute set by Register 0x401F, Bit 0
POWER SUPPLY SPECIFICATIONS
AVDD1 and AVDD2 must always be equal. Power supply measurements are taken with the sound engine processing path enabled.
Table 3.
Parameter
AVDD1, AVDD2
IOVDD
Digital I/O Current (IOVDD = 3.3 V)
Slave Mode, Analog I/O,
12.288 MHz External MCLK Input
Master Mode, MCKO Disabled
Digital I/O Current (IOVDD = 1.8 V)
Slave Mode, Analog I/O,
12.288 MHz External MCLK Input
Master Mode, MCKO Disabled
Analog Current (AVDD)
1
Test Conditions/Comments
20 pF capacitive load on all digital pins
fS = 48 kHz
Min
1.8 1
1.63
Typ
3.3
3.3
Max
3.65
3.65
Unit
V
V
0.20
mA
fS = 96 kHz
fS = 8 kHz
fS = 48 kHz
fS = 96 kHz
fS = 8 kHz
20 pF capacitive load on all digital pins
fS = 48 kHz
0.35
0.04
1.25
2.50
0.22
mA
mA
mA
mA
mA
0.10
mA
fS = 96 kHz
fS = 8 kHz
fS = 48 kHz
fS = 96 kHz
fS = 8 kHz
See Table 4
0.18
0.02
0.68
1.33
0.12
mA
mA
mA
mA
mA
The zero-cross detection of the beep path is not supported at AVDD1, AVDD2 < 2.2 V.
Rev. B | Page 8 of 84
ADAU1381
TYPICAL POWER MANAGEMENT MEASUREMENTS
Master clock = 12.288 MHz, PLL is active in integer mode at a 256 × fS input rate for fS = 48 kHz, analog and digital input tones are
−1 dBFS with a frequency of 1 kHz. Analog input and output are simultaneously active. Pseudo differential stereo input is routed to
ADCs, and DACs are routed to stereo line output with a 16 kΩ load. ADC input at −1 dBFS, DAC input at 0 dBFS. The speaker output is
disabled. The serial port is configured in slave mode. The beep path is disabled. The sound engine processing path is enabled. Current
measurements are given in units of mA rms.
Table 4. Mixer Boost and Power Management Conditions
Operating Voltage
AVDD = IOVDD = 3.3 V
Power Management Mode 1
Normal (default)
Extreme power saving
Enhanced performance
Power saving
AVDD = IOVDD = 1.8 V
Normal (default)
Extreme power saving
Enhanced performance
Power saving
1
2
Mixer Boost Mode 2
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Normal operation
Boost Level 1
Boost Level 2
Boost Level 3
Typical AVDD Current
Consumption (mA)
16.84
16.88
16.92
17.00
15.66
15.68
15.70
15.75
17.43
17.50
17.53
17.63
16.25
16.28
16.31
16.38
15.15
15.19
15.23
15.30
14.03
14.05
14.07
14.12
15.71
15.76
15.81
15.89
14.59
14.62
14.65
14.71
Typical ADC
THD + N (dB)
88.5
88.5
88.5
88.5
88.0
88.0
88.0
88.0
88.5
88.5
88.5
88.5
89.0
89.0
89.0
89.0
88.5
88.5
88.5
88.5
86.5
86.5
86.5
86.5
88.5
88.5
88.5
88.5
88.0
88.0
88.0
88.0
Typical Line Output
THD + N (dB)
93.0
93.0
93.0
93.0
87.5
87.5
87.5
87.5
94.5
94.5
94.5
94.5
90.5
90.5
90.5
90.5
89.5
89.5
89.5
89.5
85.5
85.5
85.5
85.5
90.5
90.5
90.5
90.5
88.0
88.0
88.0
88.0
Set by Register 0x4009, Bits[4:1], and Register 0x4029, Bits[5:2].
Set by Register 0x4009, Bits[6:5].
DIGITAL FILTERS
Table 5.
Parameter
ADC DECIMATION FILTER
Pass Band
Pass-Band Ripple
Transition Band
Stop Band
Stop-Band Attenuation
Group Delay
Mode
All modes, typ value is for 48 kHz
Factor
Min
0.4375 × fS
Typ
21
±0.015
24
27
0.5 × fS
0.5625 × fS
70
22.9844/fS
Rev. B | Page 9 of 84
479
Max
Unit
kHz
dB
kHz
kHz
dB
μs
ADAU1381
Parameter
DAC INTERPOLATION FILTER
Pass Band
Pass-Band Ripple
Transition Band
Stop Band
Stop-Band Attenuation
Group Delay
Mode
Factor
Min
Typ
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
48 kHz mode, typ value is for 48 kHz
96 kHz mode, typ value is for 96 kHz
0.4535 × fS
0.3646 × fS
35
22
69
Max
±0.01
±0.05
0.5 × fS
0.5 × fS
0.5465 × fS
0.6354 × fS
24
48
26
61
70
70
25/fS
11/fS
521
115
Unit
kHz
kHz
dB
dB
kHz
kHz
kHz
kHz
dB
dB
μs
μs
DIGITAL INPUT/OUTPUT SPECIFICATIONS
−25°C < TA < +85°C, IOVDD = 1.62 V to 3.63 V, unless otherwise specified.
Table 6.
Parameter
HIGH LEVEL INPUT VOLTAGE (VIH)
LOW LEVEL INPUT VOLTAGE (VIL)
INPUT LEAKAGE
HIGH LEVEL OUTPUT VOLTAGE (VOH)
LOW LEVEL OUTPUT VOLTAGE (VOL)
Conditions/Comments
IOVDD ≥ 2.97 V
1.8 V ≤ IOVDD ≤ 2.97 V
IOVDD < 1.8 V
IIH at VIH = 2.4 V
IIL at VIL = 0.8 V
IIL of MCKI
IIH with internal pull-up
IIL with internal pull-down
IIH with internal pull-up
IIL with internal pull-down
For low drive strength, IOH = 2 mA and IOL = 2 mA
at IOVDD = 3.3 V, IOH = 0.6 mA and IOL = 0.6 mA at
IOVDD = 1.8 V; for high drive strength, IOH = 3 mA
and IOL = 3 mA at IOVDD = 3.3 V, IOH = 0.9 mA and
IOL = 0.9 mA at IOVDD = 1.8 V
For low drive strength, IOH = 2 mA and IOL = 2 mA
at IOVDD = 3.3 V, IOH = 0.6 mA and IOL = 0.6 mA at
IOVDD = 1.8 V; for high drive strength, IOH = 3 mA
and IOL = 3 mA at IOVDD = 3.3 V, IOH = 0.9 mA and
IOL = 0.9 mA at IOVDD = 1.8 V
INPUT CAPACITANCE
Rev. B | Page 10 of 84
Min
0.7 × IOVDD
Typ
Max
0.3 × IOVDD
0.2 × IOVDD
0.1 × IOVDD
±0.17
±0.17
−7
±0.7
−7
5
±0.18
IOVDD − 0.4
Unit
V
V
V
V
μA
μA
μA
μA
μA
μA
μA
V
0.4
V
5
pF
ADAU1381
DIGITAL TIMING SPECIFICATIONS
−25°C < TA < +85°C, IOVDD = 1.62 V to 3.63 V, unless otherwise specified.
Table 7. Digital Timing
Parameter
MASTER CLOCK
tMP
Duty Cycle
SERIAL PORT
tBIL
tBIH
tLIS
tLIH
tSIS
tSIH
tSODM
SPI PORT
fCCLK,R
fCCLK,R
fCCLK,W
fCCLK,W
tCCPL
tCCPH
tCLS
tCLH
tCLPH
tCDS
tCDH
tCOD
I2C PORT
fSCL
tSCLH
tSCLL
tSCS
tSCH
tDS
tSCR
tSCF
tSDR
tSDF
tBFT
DIGITAL MICROPHONE
tDCF
tDCR
tDDV
tDDH
tMIN
50
30
Limit
tMAX
Unit
Description
90.9
70
ns
%
Master clock (MCLK) period (that is, period of the signal input to MCKI).
70
ns
ns
ns
ns
ns
ns
ns
BCLK pulse width low.
BCLK pulse width high.
LRCLK setup. Time to BCLK rising.
LRCLK hold. Time from BCLK rising.
DAC_SDATA setup. Time to BCLK rising.
DAC_SDATA hold. Time from BCLK rising.
ADC_SDATA delay. Time from BCLK falling in master mode.
MHz
MHz
MHz
MHz
ns
ns
ns
ns
ns
ns
ns
CCLK frequency, read operation, IOVDD = 1.8 V ± 10%.
CCLK frequency, read operation, IOVDD = 3.3 V ± 10%.
CCLK frequency, write operation, IOVDD = 1.8 V ± 10%.
CCLK frequency, write operation, IOVDD = 3.3 V ± 10%.
CCLK pulse width low.
CCLK pulse width high.
CLATCH setup. Time to CCLK rising.
CLATCH hold. Time from CCLK rising.
CLATCH pulse width high.
CDATA setup. Time to CCLK rising.
CDATA hold. Time from CCLK rising.
COUT delay from CCLK edge to valid data, IOVDD = 1.8 V ± 10%.
COUT delay from CCLK edge to valid data, IOVDD = 3.3 V ± 10%.
10
10
5
5
5
5
5
10
25
25
10
10
10
5
10
5
5
70
40
400
0.6
1.3
0.6
0.6
100
300
300
300
300
0.6
22
0
10
10
30
12
ns
kHz
μs
μs
μs
μs
ns
ns
ns
ns
ns
μs
ns
ns
ns
ns
SCL frequency.
SCL high.
SCL low.
Setup time; relevant for repeated start condition.
Hold time. After this period, the first clock is generated.
Data setup time.
SCL rise time.
SCL fall time.
SDA rise time.
SDA fall time.
Bus-free time. Time between stop and start.
RL = 1 MΩ, CL = 14 pF.
Digital microphone clock fall time.
Digital microphone clock rise time.
Digital microphone delay time for valid data.
Digital microphone delay time for data three-stated.
Rev. B | Page 11 of 84
ADAU1381
Digital Timing Diagrams
tLIH
tBIH
BCLK
tBIL
tLIS
LRCLK
tSIS
DAC_SDATA
LEFT-JUSTIFIED
MODE
MSB
MSB – 1
tSIH
tSIS
DAC_SDATA
I2S MODE
MSB
tSIH
tSIS
tSIS
DAC_SDATA
RIGHT-JUSTIFIED
MODE
LSB
MSB
tSIH
tSIH
8-BIT CLOCKS
(24-BIT DATA)
12-BIT CLOCKS
(20-BIT DATA)
08313-002
14-BIT CLOCKS
(18-BIT DATA)
16-BIT CLOCKS
(16-BIT DATA)
Figure 2. Serial Input Port Timing
tBIH
BCLK
tBIL
LRCLK
ADC_SDATA
LEFT-JUSTIFIED
MODE
tSODM
MSB
MSB – 1
tSODM
ADC_SDATA
I2S MODE
MSB
tSODM
ADC_SDATA
RIGHT-JUSTIFIED
MODE
MSB
LSB
8-BIT CLOCKS
(24-BIT DATA)
12-BIT CLOCKS
(20-BIT DATA)
08313-003
14-BIT CLOCKS
(18-BIT DATA)
16-BIT CLOCKS
(16-BIT DATA)
Figure 3. Serial Output Port Timing
Rev. B | Page 12 of 84
ADAU1381
tCLS
tCLH
tCLPH
tCCPL
tCCPH
CLATCH
CCLK
CDATA
tCDH
tCDS
COUT
08313-004
tCOD
Figure 4. SPI Port Timing
tSDR
tSCH
tDS
tSCH
SDA
tSDF
tSCR
SCL
tSCLL
tSCS
tSCF
tBFT
2
Figure 5. I C Port Timing
tDCF
tDCR
CLK
DATA1/
DATA2 DATA1
DATA2
tDDH
tDDV
tDDV
DATA1
DATA2
Figure 6. Digital Microphone Timing
Rev. B | Page 13 of 84
08313-106
tDDH
08313-005
tSCLH
ADAU1381
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 8.
Parameter
Power Supply (AVDD1 = AVDD2)
Input Current (Except Supply Pins)
Analog Input Voltage (Signal Pins)
Digital Input Voltage (Signal Pins)
Operating Temperature Range (Case)
Storage Temperature Range
Rating
−0.3 V to +3.9 V
±20 mA
–0.3 V to VDD + 0.3 V
−0.3 V to VDD + 0.3 V
−25°C to +85°C
−65°C to +150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
In Table 9, θJA is the junction-to-ambient thermal resistance, θJB is
the junction-to-board thermal resistance, θJC is the junction-to-case
thermal resistance, ψJB is the in-use junction-to-top of package thermal resistance, and ψJT is the in-use junction-to-board thermal
resistance. All characteristics are for a 4-layer board.
Table 9. Thermal Resistance
Package Type
32-Lead LFCSP
30-Ball WLCSP
ESD CAUTION
Rev. B | Page 14 of 84
θJA
35
39
θJB
19
7
θJC
2.5
0.5
ψJB
18
ψJT
0.3
Unit
°C/W
°C/W
ADAU1381
32
31
30
29
28
27
26
25
MICBIAS
BEEP
LMIC/LMICN/MICD1
LMICP
RMICP
RMIC/RMICN/MICD2
AOUTL
AOUTR
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
4
5
6
7
8
PIN 1
INDICATOR
ADAU1381
TOP VIEW
(Not to Scale)
24
23
22
21
20
19
18
17
NC
AGND2
SPP
NC
SPN
AVDD2
MCKO
MCKI
NOTES
1. NC = NO CONNECT.
2. THE EXPOSED PAD IS CONNECTED INTERNALLY TO THE
ADAU1381 GROUNDS. FOR INCREASED RELIABILITY OF THE
SOLDER JOINTS AND MAXIMUM THERMAL CAPABILITY, IT IS
RECOMMENDED THAT THE PAD BE SOLDERED TO THE
GROUND PLANE.
08313-007
SDA/COUT
ADDR0/CDATA
ADDR1/CLATCH
IOVDD
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
9
10
11
12
13
14
15
16
CM
PDN
AGND1
AVDD1
DVDDOUT
DGND
GPIO
SCL/CCLK
1
2
3
4
5
6
A
AGND2
AOUTL
RMICP
LMIC/
LIMICN/
MICD1
MICBIAS
CM
B
SPP
AOUTR
RMIC/
RMICN/
MICD2
LMICP
BEEP
AGND1
C
SPN
LRCLK/
GPIO3
ADDR0/
CDATA
SCL/
CCLK
PDN
AVDD1
D
AVDD2
MCKO
ADC_
SDATA/
GPIO1
ADDR1/
CLATCH
GPIO
DVDDOUT
E
MCKI
BCLK/
GPIO2
DAC_
SDATA/
GPIO0
IOVDD
SDA/
COUT
DGND
TOP VIEW
(BALL SIDE DOWN)
Not to Scale
Figure 8. 30-Ball, 6 × 5 WLCSP Pin Configuration (Bottom View)
Rev. B | Page 15 of 84
08313-008
Figure 7. 32-Lead LFCSP Pin Configuration
ADAU1381
Table 10. Pin Function Descriptions
Pin No.
LFCSP
1
WLCSP
A6
Mnemonic
CM
Type 1
A_OUT
2
C5
PDN
A_IN
3
4
5
B6
C6
D6
AGND1
AVDD1
DVDDOUT
PWR
PWR
PWR
6
7
8
9
10
11
12
E6
D5
C4
E5
C3
D4
E4
DGND
GPIO
SCL/CCLK
SDA/COUT
ADDR0/CDATA
ADDR1/CLATCH
IOVDD
PWR
D_IO
D_IN
D_IO
D_IN
D_IN
PWR
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
E3
D3
E2
C2
E1
D2
D1
C1
N/A
B1
A1
N/A
B2
A2
B3
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
MCKI
MCKO
AVDD2
SPN
NC
SPP
AGND2
NC
AOUTR
AOUTL
RMIC/RMICN/MICD2
D_IO
D_IO
D_IO
D_IO
D_IN
D_OUT
PWR
A_OUT
28
29
30
A3
B4
A4
RMICP
LMICP
LMIC/LMICN/MICD1
A_IN
A_IN
A_IN
31
32
B5
A5
BEEP
MICBIAS
THERM_PAD
(Exposed Pad)
A_IN
PWR
1
A_OUT
PWR
A_OUT
A_OUT
A_IN
Description
VDD/2 V Common-Mode Reference. A 10 μF to 47 μF decoupling capacitor should be
connected between this pin and ground to reduce crosstalk between the ADCs and
DACs. The material of the capacitors is not critical. This pin can be used to bias external
analog circuits, as long as they are not drawing current from CM (for example, the
noninverting input of an op amp).
Power-Down. Connecting this pin to GND powers down the chip. Resides in AVDD1
domain.
Analog Ground.
Analog Power Supply. Should be equivalent to AVDD2.
Digital Core Supply Decoupling Point. The digital supply is generated from an onboard regulator and does not require an external supply. DVDDOUT should be
decoupled to DGND with a 100 nF capacitor.
Digital Ground.
Dedicated General-Purpose Input/Output.
I2C Clock/SPI Clock.
I2C Data/SPI Data Output.
I2C Address 0/SPI Data Input.
I2C Address 1/SPI Latch Signal.
Supply for Digital Input and Output Pins. The digital output pins are supplied from
IOVDD, which sets the highest allowed input voltage for the digital input pins. The
current draw of this pin is variable because it is dependent on the loads of the digital
outputs. IOVDD should be decoupled to DGND with a 100 nF capacitor.
DAC Serial Input Data/General-Purpose Input and Output.
ADC Serial Output Data/General-Purpose Input and Output.
Serial Data Port Bit Clock/General-Purpose Input and Output.
Serial Data Port Frame Clock/General-Purpose Input and Output.
Master Clock Input.
Master Clock Output.
Analog Power Supply. Should be equivalent to AVDD1.
Speaker Amplifier Negative Signal Output.
No Connect.
Speaker Amplifier Positive Signal Output.
Speaker Amplifier Ground.
No Connect.
Line Output Amplifier, Right Channel.
Line Output Amplifier, Left Channel.
Right Channel Input from Single-Ended Source/Right Channel Input from Negative
Pseudo Differential Source/Digital Microphone Input 2.
Right Channel Input from Positive Pseudo Differential Source.
Left Channel Input from Positive Pseudo Differential Source.
Left Channel Input from Single-Ended Source/Left Channel Input from Negative
Pseudo Differential Source/Digital Microphone Input 1.
Beep Signal Input.
Microphone Bias.
Exposed Pad. The exposed pad is connected internally to the ADAU1381 grounds. For
increased reliability of the solder joints and maximum thermal capability, it is
recommended that the pad be soldered to the ground plane.
A_OUT = analog output, A_IN = analog input, PWR = power, D_IO = digital input/output, D_OUT = digital output, and D_IN = digital input.
Rev. B | Page 16 of 84
ADAU1381
0
0.10
–10
0.08
–20
0.06
–30
0.04
MAGNITUDE (dBFS)
–40
–50
–60
–70
0.02
0
–0.02
–0.04
–80
–0.06
–90
–0.08
–0.10
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
FREQUENCY (NORMALIZED TO fS)
08313-009
–100
Figure 9. ADC Decimation Filter, 64× Oversampling,
Normalized to fS
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
08313-012
MAGNITUDE (dBFS)
TYPICAL PERFORMANCE CHARACTERISTICS
0.50
FREQUENCY (NORMALIZED TO fS)
Figure 12. ADC Decimation Filter Pass-Band Ripple, 128× Oversampling,
Normalized to fS
0
0.04
–10
–20
–30
MAGNITUDE (dBFS)
MAGNITUDE (dBFS)
0.02
0
–0.02
–0.04
–40
–50
–60
–70
–80
–0.06
–90
0.10
0.15
0.20
0.25
0.30
0.35
0.40
FREQUENCY (NORMALIZED TO fS)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
FREQUENCY (NORMALIZED TO fS)
1.0
08313-013
0.05
08313-010
0
–100
Figure 13. ADC Decimation Filter, Double-Rate Mode,
Normalized to fS
Figure 10. ADC Decimation Filter Pass-Band Ripple, 64× Oversampling,
Normalized to fS
0
0.04
–10
0.02
MAGNITUDE (dBFS)
–30
–40
–50
–60
–70
0
–0.02
–0.04
–80
–100
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
FREQUENCY (NORMALIZED TO fS)
Figure 11. ADC Decimation Filter, 128× Oversampling,
Normalized to fS
1.0
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
FREQUENCY (NORMALIZED TO fS)
0.40
08313-014
–0.06
–90
08313-011
MAGNITUDE (dBFS)
–20
Figure 14. ADC Decimation Filter Pass-Band Ripple, Double-Rate Mode,
Normalized to fS
Rev. B | Page 17 of 84
0
0.05
–10
0.04
–20
0.03
–30
0.02
MAGNITUDE (dBFS)
–40
–50
–60
–70
0.01
0
–0.01
–0.02
–80
–0.03
–90
–0.04
–0.05
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
FREQUENCY (NORMALIZED TO fS)
08313-015
–100
Figure 15. DAC Interpolation Filter, 64× Oversampling,
Normalized to fS
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
FREQUENCY (NORMALIZED TO fS)
08313-018
MAGNITUDE (dBFS)
ADAU1381
Figure 18. DAC Interpolation Filter Pass-Band Ripple, 128× Oversampling,
Normalized to fS
0.20
0
–10
0.15
–20
MAGNITUDE (dBFS)
MAGNITUDE (dBFS)
0.10
0.05
0
–0.05
–30
–40
–50
–60
–70
–0.10
–80
–0.15
–90
0.10
0.15
0.20
0.25
0.30
0.35
0.40
FREQUENCY (NORMALIZED TO fS)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
08313-019
0.05
0.40
08313-020
–100
0
08313-016
–0.20
FREQUENCY (NORMALIZED TO fS)
Figure 16. DAC Interpolation Filter Pass-Band Ripple, 64× Oversampling,
Normalized to fS
Figure 19. DAC Interpolation Filter, Double-Rate Mode,
Normalized to fS
0
0.20
–10
0.15
–20
MAGNITUDE (dBFS)
–40
–50
–60
–70
0.05
0
–0.05
–0.10
–80
–0.15
–90
–100
–0.20
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
FREQUENCY (NORMALIZED TO fS)
Figure 17. DAC Interpolation Filter, 128× Oversampling,
Normalized to fS
1.0
08313-017
MAGNITUDE (dBFS)
0.10
–30
0
0.05
0.10
0.15
0.20
0.25
0.30
FREQUENCY (NORMALIZED TO fS)
0.35
Figure 20. DAC Interpolation Filter Pass-Band Ripple, Double-Rate Mode,
Normalized to fS
Rev. B | Page 18 of 84
ADAU1381
0
0
–10
–20
–20
–40
THD + N (dB)
THD + N (dB)
–30
–50
–60
–40
–60
–70
–80
–80
–90
1
10
100
SPEAKER OUTPUT POWER (mW)
600
Figure 21. THD + N vs. Speaker Output Power, 8 Ω Load, 3.3 V Supply
1
10
SPEAKER OUTPUT POWER (mW)
100
08313-122
–100
08313-121
–100
Figure 22. THD + N vs. Speaker Output Power, 8 Ω Load, 1.8 V Supply
Rev. B | Page 19 of 84
ADAU1381
SYSTEM BLOCK DIAGRAMS
IOVDD
10µF
AVDD1
10µF
10µF
+
+
0.1µF
0.1µF
+
AVDD2
47µF
0.1µF
+
MICBIAS
8Ω
SPEAKER
OUT
–
0.1µF
0.1µF
49.9kΩ
AVDD2
AVDD1
DVDDOUT
10µF
IOVDD
DIFFERENTIAL INPUT
(LEFT)
MICBIAS
+
100pF
LMIC/LMICN/MICD1
SPN
LMICP
SPP
10kΩ
10kΩ
10Ω 220µF
AOUTL
10µF
STEREO SINGLE-ENDED
HEADPHONE OUTPUT
49.9kΩ
10kΩ
ADAU1381
100pF
DIFFERENTIAL INPUT
(RIGHT)
10µF
10kΩ
RMIC/RMICN/MICD2
49.9kΩ
LEFT_OUT
+
AOUTR
10kΩ
10kΩ
10Ω 220µF
+
RMICP
CM
10µF
100nF
+
RIGHT_OUT
10µF
49.9kΩ
GPIO
10µF
STEREO
HEADPHONE
AMPLIFIER
GPIO
BEEP
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
EXTERNAL
BEEP INPUT
MCKI
PDN
PDN
08313-021
MCKO
SYSTEM
CONTROLLER
AGND2
49.9Ω
AGND1
ADDR1/CLATCH
ADDR0/CDATA
SDA/COUT
SCL/CCLK
2.2pF
DGND
MCKO
49.9Ω
THERM_PAD
(EXPOSED PAD)
EXTERNAL
MCLK SOURCE
SERIAL
DATA
Figure 23. System Block Diagram with Differential Inputs
Rev. B | Page 20 of 84
ADAU1381
IOVDD
10µF
AVDD1
10µF
10µF
+
+
0.1µF
0.1µF
+
AVDD2
47µF
0.1µF
+
MICBIAS
8Ω
SPEAKER
OUT
–
0.1µF
0.1µF
2kΩ
AVDD2
AVDD1
DVDDOUT
MICBIAS
IOVDD
MICBIAS
+
100pF
SPN
0.1µF
10kΩ
SPP
ANALOG
MIC 1
LMIC/LMICN/MICD1
10µF
10kΩ
LMICP
AOUTR
CM
ADAU1381
ANALOG
MIC 2
10kΩ
10kΩ
0.1µF
10kΩ
10kΩ
10Ω 220µF
10µF
+
RMIC/RMICN/MICD2
49.9kΩ
LEFT_OUT
100pF
MICBIAS
2kΩ
10Ω 220µF
AOUTL
CM
+
49.9kΩ
STEREO SINGLE-ENDED
HEADPHONE OUTPUT
CM
CM
RMICP
100nF
+
RIGHT_OUT
10µF
GPIO
10µF
STEREO
HEADPHONE
AMPLIFIER
GPIO
BEEP
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
EXTERNAL
BEEP INPUT
MCKI
MCKO
PDN
08313-022
PDN
SYSTEM
CONTROLLER
AGND2
49.9Ω
AGND1
ADDR1/CLATCH
ADDR0/CDATA
SDA/COUT
SCL/CCLK
2.2pF
DGND
MCKO
49.9Ω
THERM_PAD
(EXPOSED PAD)
EXTERNAL
MCLK SOURCE
SERIAL
DATA
Figure 24. System Block Diagram with Analog Microphone Inputs
Rev. B | Page 21 of 84
ADAU1381
IOVDD
10µF
AVDD1
10µF
10µF
+
+
0.1µF
0.1µF
+
AVDD2
47µF
0.1µF
+
MICBIAS
8Ω
SPEAKER
OUT
–
0.1µF
0.1µF
AVDD2
AVDD1
DVDDOUT
IOVDD
MICBIAS
+
100pF
SPN
SINGLE-ENDED
STEREO INPUT
10kΩ
SPP
10kΩ
10µF
CM
49.9kΩ
10Ω 220µF
AOUTL
LMIC/LMICN/MICD1
AOUTR
LMICP
LEFT_OUT
+
1kΩ
STEREO SINGLE-ENDED
HEADPHONE OUTPUT
10kΩ
CM
ADAU1381
100pF
10µF
1kΩ
RMIC/RMICN/MICD2
10kΩ
CM
49.9kΩ
10kΩ
10kΩ
10Ω 220µF
+
RMICP
CM
100nF
+
RIGHT_OUT
10µF
GPIO
10µF
STEREO
HEADPHONE
AMPLIFIER
GPIO
BEEP
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
EXTERNAL
BEEP INPUT
MCKI
MCKO
PDN
08313-023
PDN
SYSTEM
CONTROLLER
AGND2
49.9Ω
AGND1
ADDR1/CLATCH
ADDR0/CDATA
SDA/COUT
SCL/CCLK
2.2pF
DGND
MCKO
49.9Ω
THERM_PAD
(EXPOSED PAD)
EXTERNAL
MCLK SOURCE
SERIAL
DATA
Figure 25. System Block Diagram with Single-Ended Stereo Line Inputs
Rev. B | Page 22 of 84
ADAU1381
IOVDD
10µF
AVDD1
10µF
10µF
+
+
0.1µF
0.1µF
+
AVDD2
47µF
0.1µF
+
MICBIAS
8Ω
SPEAKER
OUT
–
0.1µF
0.1µF
AVDD2
AVDD1
DVDDOUT
IOVDD
MICBIAS
+
100pF
SPN
BCLK OR MCLKO
10kΩ
SPP
10kΩ
10Ω 220µF
AOUTL
LMIC/LMICN/MICD1
AOUTR
LMICP
10kΩ
ADAU1381
100pF
RMIC/RMICN/MICD2
10kΩ
10kΩ
RMICP
10kΩ
10Ω 220µF
+
1kΩ
LEFT_OUT
+
STEREO DIGITAL
MIC INPUT
STEREO SINGLE-ENDED
HEADPHONE OUTPUT
CM
100nF
+
RIGHT_OUT
10µF
GPIO
10µF
STEREO
HEADPHONE
AMPLIFIER
GPIO
BEEP
DAC_SDATA/GPIO0
ADC_SDATA/GPIO1
BCLK/GPIO2
LRCLK/GPIO3
EXTERNAL
BEEP INPUT
MCKI
MCKO
PDN
08313-024
PDN
SYSTEM
CONTROLLER
AGND2
49.9Ω
AGND1
ADDR1/CLATCH
ADDR0/CDATA
SDA/COUT
SCL/CCLK
2.2pF
DGND
MCKO
BCLK
49.9Ω
THERM_PAD
(EXPOSED PAD)
EXTERNAL
MCLK SOURCE
SERIAL
DATA
Figure 26. System Block Diagram with Stereo Digital Microphone Inputs
Rev. B | Page 23 of 84
ADAU1381
THEORY OF OPERATION
The ADAU1381 is a low power audio codec with an integrated,
fixed-function audio processing sound engine. It is an all-in-one
package that offers high quality audio, low power, small size, and
many advanced features. The stereo ADC and stereo DAC each
have a dynamic range (DNR) performance of at least 96.5 dB and
a total harmonic distortion plus noise (THD + N) performance
of at least −90 dB. The serial data port is compatible with I2S, leftjustified, right-justified, and TDM modes for interfacing to digital
audio data. The operating voltage range is 1.8 V to 3.65 V, with
an on-board regulator generating the internal digital supply voltage.
The record path includes very flexible input configurations that
can accept differential or single-ended analog microphone inputs
as well as two stereo digital microphone inputs. There is also a
beep input pin (BEEP) dedicated to analog beep signals that are
common in digital still camera applications. A microphone bias
pin that can power electrets-type microphones is also available.
Each input signal has its own programmable gain amplifier (PGA)
for input volume adjustment. An automatic level control (ALC)
is built into the sound engine to maintain a constant input recording volume.
The ADCs and DACs are high quality, 24-bit Σ-Δ converters
that operate at selectable 64× or 128× oversampling rates. The
base sampling rate of the converters is set by the input clock rate
and can be further scaled with the converter control register
settings. The converters can operate at sampling frequencies
from 8 kHz to 96 kHz. The ADCs and DACs also include very
fine-step digital volume controls.
The playback path allows input signals and DAC outputs to be
mixed into speaker and/or line outputs. The speaker driver is
capable of driving 400 mW into an 8 Ω load.
The fixed-function sound engine contains a digital audio
processing flow optimized for digital still camera stereo audio
processing. However, the flexibility offered by the built-in
sound engine allows this codec to be used for a wide variety of
low power applications. Signal processing blocks included in the
sound engine include the following:
•
•
•
•
•
•
•
•
Wind noise detection and autofiltering
Dual-band compression with programmable crossover,
compression curves, and timing
Programmable multiband equalizer
Configurable notch filter
Enhanced stereo capture algorithm
Automatic level control
Digital volume control
Multiplexers for signal routing
The ADAU1381 can generate its internal clocks from a wide
range of input clocks by using the on-board fractional PLL.
The PLL accepts inputs from 11 MHz to 20 MHz.
The ADAU1381 is provided in a small, 32-lead, 5 mm × 5 mm
lead frame chip scale package (LFCSP) with an exposed bottom
pad, or a 30-ball (6 × 5 bump), 3.4 mm × 2.64 mm wafer level
chip scale package (WLCSP).
Rev. B | Page 24 of 84
ADAU1381
STARTUP, INITIALIZATION, AND POWER
POWER-UP SEQUENCE
This section details the procedure for setting up the ADAU1381
properly. Figure 27 provides an overview of how to initialize the IC.
If AVDD1 and AVDD2 are from the same supply, they can
power up simultaneously. If AVDD1 and AVDD2 are from
separate supplies, then AVDD1 should be powered up first.
IOVDD should be applied simultaneously with AVDD1, if
possible.
START
ARE AVDD1 AND AVDD2
SUPPLIED SEPARATELY?
YES
NO
NO
CAN AVDD1 AND AVDD2
BE SIMULTANEOUSLY
SUPPLIED?
The ADAU1381 uses a power-on reset (POR) circuit to reset the
registers upon power-up. The POR monitors the DVDDOUT
pin and generates a reset signal whenever power is applied to
the chip. During the reset, the ADAU1381 is set to the default
values documented in the register map (see the Control Register
Map section).
YES
SUPPLY POWER
TO AVDD1
SUPPLY POWER TO AVDD1/AVDD2
PINS SIMULTANEOUSLY
SUPPLY POWER
TO AVDD2
The POR is also used to prevent clicks and pops on the speaker
driver output. The power-up sequencing and timing involved is
described in Figure 28 in this section, and in Figure 36 and
Figure 37 of the Speaker Output section.
SUPPLY POWER TO IOVDD
WAIT 14ms FOR POWER-ON RESET
AND INITIALIZATION ROM BOOT
A self-boot ROM initializes the memories after the POR has
completed. When the self-boot sequence is complete, the control
registers are accessible via the I2C/SPI control port and should
then be configured as required for the application. Typically,
with a 10 μF capacitor on AVDD1, the power supply ramp-up,
POR, and self-boot combined take approximately 14 ms.
CONFIGURE CLOCK GENERATION
REGISTER 16384 (0x4000)
AND REGISTER 16386 (0x4002)
WAIT FOR PLL LOCK
(2.4ms TO 3.5ms)
ENABLE DIGITAL POWER TO
FUNCTIONAL SUBSYSTEMS
REGISTER 16512 (0x4080)
AND REGISTER 16513 (0x4081)
08313-025
SET UP SOUND ENGINE REGISTERS
FOR CUSTOMIZED SIGNAL PATH
(INCLUDING VOLUME, SAMPLE RATES,
FILTER COEFFICIENTS)
INITIALIZATION
COMPLETE
Figure 27. Initialization Sequence
MAIN SUPPLY ENABLED
MAIN SUPPLY DISABLED
AVDD1
1.5V
AVDD2
1.5V
DVDDOUT
1.35V
POWER-UP
(INTERNAL
SIGNAL)
0.95V
POR
ACTIVE
POR ACTIVATES
POR COMPLETE/SELF-BOOT INITIATES
SELF-BOOT COMPLETE/MEMORY
IS ACCESSIBLE
IOVDD
14ms
INPUT/OUTPUT
PINS
HIGH-Z
ACTIVE
Figure 28. Power-Up and Power-Down Sequence Timing Diagram
Rev. B | Page 25 of 84
HIGH-Z
08313-026
INTERNAL MCLK
(NOT TO SCALE)
ADAU1381
CLOCK GENERATION AND MANAGEMENT
The ADAU1381 uses a flexible clocking scheme that enables the
use of many different input clock rates. The PLL can be bypassed
or used, resulting in two different approaches to clock management. For more information about clocking schemes, PLL
configuration, and sampling rates, see the Clocking and
Sampling Rates section.
Case 1: PLL Is Bypassed
If the PLL is bypassed, the core clock is derived directly from
the master clock (MCLK) input. The rate of this clock must be
set properly in Register 16384 (0x4000), clock control, Bits[2:1],
input master clock frequency. When the PLL is bypassed,
supported external clock rates are 256 × fS, 512 × fS, 768 × fS,
and 1024 × fS, where fS is the base sampling rate. The core clock
of the chip is off until Register 16384 (0x4000), clock control,
Bit 0, core clock enable, is set to 1.
Case 2: PLL Is Used
The core clock to the entire chip is off during the PLL lock
acquisition period. The user can poll the lock bit to determine
when the PLL has locked. After lock is acquired, the ADAU1381
can be started by setting Register 16384 (0x4000), clock control,
Bit 0, core clock enable, to 1.This bit enables the core clock to all
the internal functional blocks of the ADAU1381.
PLL Lock Acquisition
During the lock acquisition period, only Register 16384 (0x4000),
clock control, and Register 16386 (0x4002), PLL control, are
accessible through the control port. Reading from or writing to
any other address is prohibited until Register 16384 (0x4000),
clock control, Bit 0, core clock enable, and Register 16386 (0x4002),
PLL control, Bit 1, PLL lock, are set to 1.
Register 16386 (0x4002), PLL control, is a 48-bit register for which
all bits must be written with a single continuous write to the
control port.
The PLL lock time is dependent on the MCLK rate. Typical lock
times are provided in Table 11.
Table 11. PLL Lock Time
PLL Mode
Fractional
Integer
Fractional
Fractional
Fractional
Fractional
Fractional
MCLK Frequency
12 MHz
12.288 MHz
13 MHz
14.4 MHz
19.2 MHz
19.68 MHz
19.8 MHz
Lock Time (Typical)
3.0 ms
2.96 ms
2.4 ms
2.4 ms
2.98 ms
2.98 ms
2.98 ms
ENABLING DIGITAL POWER TO FUNCTIONAL
SUBSYSTEMS
To power subsystems in the device, they must be enabled using
Register 16512 (0x4080), Digital Power-Down 0, and Register
16513 (0x4081), Digital Power-Down 1. The exact settings depend
on the application. However, to proceed with the initialization
sequence and access the RAMs and registers of the ADAU1381,
Register 16512 (0x4080), Digital Power-Down 0, Bit 6, memory
controller, and Bit 0, sound engine, must be enabled.
SETTING UP THE SOUND ENGINE
After the PLL has locked, the ADAU1381 is in an operational
state, and the control port can be used to configure the sound
engine. For more information, see the Sound Engine section.
POWER REDUCTION MODES
Sections of the ADAU1381 chip can be turned on and off as
needed to reduce power consumption. These include the ADCs,
the DACs, and the PLL.
In addition, some functions can be set in the registers to operate
in power saving, normal, or enhanced performance operation.
See the respective portions of the General-Purpose Input/Outputs
section for more information.
Each digital filter of the ADCs and DACs can be set to a 64× or
128× (default) oversampling ratio. Setting the oversampling ratio
to 64× lowers power consumption with a minimal impact on
performance. See the Typical Performance Characteristics section
and the Typical Power Management Measurements section for
specifications and graphs of the filters.
Detailed information regarding individual power reduction control
registers can be found in the Control Register Map section of this
document.
Power-Down Pin (PDN)
The power-down pin provides a simple hardware-based
method for initiating low power mode without requiring access
via the control port. When the PDN pin is lowered to the same
potential as ground, the internal digital regulator is disabled
and the device ceases to function, with power consumption
dropping to a very low level. The common-mode voltage sinks,
and all internal memories and registers lose their contents.
When the PDN pin is raised back to the same potential as
AVDD1, the device reinitializes in its default state, as described
in the Power-Up Sequence section.
POWER-DOWN SEQUENCE
When powering down the device, the IOVDD, AVDD1, and
AVDD2 supplies should be disabled at the same time, if possible,
but only after the analog and speaker outputs have been muted. If
the supplies cannot be disabled simultaneously, the preferred
sequence is IOVDD first, AVDD2 second, and AVDD1 last.
Rev. B | Page 26 of 84
ADAU1381
CLOCKING AND SAMPLING RATES
SOUND ENGINE
FRAME RATE
fS /
0.5, 1, 1.5, 2, 3, 4, 6
CORE
CLOCK
AUTOMATICALLY SET TO 1024 × fS
WHEN PLL CLOCK SOURCE SELECTED
CONVERTER
SAMPLING RATE
ADCs
DACs
fS /
0.5, 1, 1.5, 2, 3, 4, 6
SERIAL PORT
SAMPLING RATE
SERIAL DATA
INPUT/OUTPUT
PORTS
ADC_SDATA/GPIO1
fS /
0.5, 1, 1.5, 2, 3, 4, 6
08313-027
INPUT DIVIDE
1, 2, 3, 4
INPUT MASTER
CLOCK FREQUENCY
256 × fS, 512 × fS,
768 × fS, 1024 × fS
DAC_SDATA/GPIO0
MCKI
f × (R + N/M)
INTEGER, NUMERATOR,
DENOMINATOR
BCLK/GPIO2
f/X
CLOCK CONTROL
LRCLK/GPIO3
PLL CONTROL
SOUND
ENGINE
Figure 29. Clock Routing Diagram
CORE CLOCK
The core clock divider generates a core clock either from the
PLL or directly from MCLK and can be set in Register 16384
(0x4000), clock control.
The core clock is always in 256 × fS mode. Direct MCLK frequencies must correspond to a value listed in Table 12, where fS
is the base sampling frequency. PLL outputs are always in 1024
× fS mode, and the clock control register automatically sets the
core clock divider to f/4 when using the PLL.
For example, if the input to Bit 3 = 49.152 MHz (from PLL),
then Bits[2:1] = 1024 × fS; therefore,
fS = 49.152 MHz/1024 = 48 kHz
Table 13. Clock Control Register (Register 16384, 0x4000)
Bits
3
Bit Name
Clock source select
[2:1]
Input master clock
frequency
0
Core clock enable
Table 12. Core Clock Frequency Dividers
Input Clock Rate
256 × fS
512 × fS
768 × fS
1024 × fS
Core Clock Divider
f/1
f/2
f/3
f/4
Core Clock
256 × fS
Settings
0: direct from MCKI pin (default)
1: PLL clock
00: 256 × fS (default)
01: 512 × fS
10: 768 × fS
11: 1024 × fS
0: core clock disabled (default)
1: core clock enabled
SAMPLING RATES
Clocks for the converters, the serial ports, and the sound engine are
derived from the core clock. The core clock can be derived directly
from MCLK, or it can be generated by the PLL. Register 16384
(0x4000), clock control, Bit 3, clock source select, determines
the clock source.
Bits[2:1], input master clock frequency, should be set according
to the expected input clock rate selected by Bit 3, clock source
select. The clock source select value also determines the core
clock rate and the base sampling frequency, fS.
The ADCs, DACs, and serial port share a common sampling
rate that is set in Register 16407 (0x4017), Converter Control 0.
Bits[2:0], converter sampling rate, set the sampling rate as a ratio of
the base sampling frequency. The sound engine sampling rate is
set in Register 16619 (0x40EB), sound engine frame rate, Bits[3:0],
sound engine frame rate, and the serial port sampling rate is set
in Register 16632 (0x40F8), serial port sampling rate, Bits[2:0],
serial port control sampling rate.
It is strongly recommended that the sampling rates for the
converters, serial ports, and sound engine be set to the same
value, unless appropriate compensation filtering is done within
the sound engine.
Rev. B | Page 27 of 84
ADAU1381
Fractional Mode
Table 14 and Table 15 list the sampling rate divisions for
common base sampling rates.
Fractional mode is used when the MCLK is a fractional
(R + (N/M)) multiple of the PLL output.
Table 14. Base Sampling Rate Divisions for fS = 48 kHz
Base Sampling
Frequency
fS = 48 kHz
For example, if MCLK = 12 MHz and fS = 48 kHz, then
Sampling Rate Scaling
fS/1
fS/6
fS/4
fS/3
fS/2
fS/1.5
fS/0.5
Sampling Rate
48 kHz
8 kHz
12 kHz
16 kHz
24 kHz
32 kHz
96 kHz
Table 15. Base Sampling Rate Divisions for fS = 44.1 kHz
Base Sampling
Frequency
fS = 44.1 kHz
Sampling Rate Scaling
fS/1
fS/6
fS/4
fS/3
fS/2
fS/1.5
fS/0.5
Sampling Rate
44.1 kHz
7.35 kHz
11.025 kHz
14.7 kHz
22.05 kHz
29.4 kHz
88.2 kHz
PLL Required Output = 1024 × 48 kHz = 49.152 MHz
R + (N/M) = 49.152 MHz/12 MHz = 4 + (12/125)
Common fractional PLL parameter settings for 44.1 kHz and
48 kHz sampling rates can be found in Table 16 and Table 17.
Table 16. Fractional PLL Parameter Settings for fS = 44.1 kHz1
MCLK
Input
(MHz)
12
13
14.4
19.2
19.68
19.8
1
Input
Divider
(X)
1
1
2
2
2
2
Integer
(R)
3
3
6
4
4
4
Denominator
(M)
625
8125
125
125
1025
1375
Numerator
(N)
477
3849
34
88
604
772
Desired core clock = 11.2896 MHz, PLL output = 45.1584 MHz.
Table 17. Fractional PLL Parameter Settings for fS = 48 kHz1
PLL
The PLL uses the MCLK as a reference to generate the core
clock. PLL settings are set in Register 16386 (0x4002), PLL
control. Depending on the MCLK frequency, the PLL must be
set for either integer or fractional mode. The PLL can accept
input frequencies in the range of 11 MHz to 20 MHz.
All six bytes in the PLL control register must be written with a
single continuous write to the control port.
MCKI
÷X
× (R + N/M)
1
08313-028
TO PLL
CLOCK DIVIDER
MCLK
Input
(MHz)
12
13
14.4
19.2
19.68
19.8
Input
Divider
(X)
1
1
2
2
2
2
Integer
(R)
4
3
6
5
4
4
Denominator
(M)
125
1625
75
25
205
825
Numerator
(N)
12
1269
62
3
204
796
Desired core clock = 12.288 MHz, PLL output = 49.152 MHz.
The PLL outputs a clock in the range of 41 MHz to 54 MHz,
which should be taken into account when calculating PLL
values and MCLK frequencies.
Figure 30. PLL Block Diagram
Integer Mode
Integer mode is used when the MCLK is an integer (R) multiple
of the PLL output (1024 × fS).
For example, if MCLK = 12.288 MHz and fS = 48 kHz, then
PLL Required Output = 1024 × 48 kHz = 49.152 MHz
R = 49.152 MHz/12.288 MHz = 4
In integer mode, the values set for N and M are ignored.
Rev. B | Page 28 of 84
ADAU1381
The ADC and DAC sampling rate can be set in Register 16407
(0x4017), Converter Control 0, Bits[2:0], converter sampling
rate. The sound engine sampling rate and serial port sampling
rate are similarly set in Register 16619 (0x40EB), sound engine
frame rate, Bits[3:0], sound engine frame rate, and Register
16632 (0x40F8), serial port sampling rate, Bits[2:0], serial port
control sampling rate, respectively.
Table 18. Sampling Rates for 256 × 48 kHz Core Clock
Core Clock
12.288 MHz
Table 18 and Table 19 depict example sampling rate settings.
The (1 × 256) case is the base sampling rate.
Sampling Rate Divider
(1 × 256)
(6 × 256)
(4 × 256)
(3 × 256)
(2 × 256)
(1.5 × 256)
(0.5 × 256)
Sampling Rate
48 kHz
8 kHz
12 kHz
16 kHz
24 kHz
32 kHz
96 kHz
Table 19. Sampling Rates for 256 × 44.1 kHz Core Clock
Core Clock
11.2896 MHz
Rev. B | Page 29 of 84
Sampling Rate Divider
(1 × 256)
(6 × 256)
(4 × 256)
(3 × 256)
(2 × 256)
(1.5 × 256)
(0.5 × 256)
Sampling Rate
44.1 kHz
7.35 kHz
11.025 kHz
14.7 kHz
22.05 kHz
29.4 kHz
88.2 kHz
ADAU1381
RECORD SIGNAL PATH
Analog Beep Input
BEEP
PGA
The BEEP pin is used for mono single-ended signals, such as a
beep warning. This signal bypasses the ADCs and the sound
engine and is mixed directly into any of the analog outputs.
LMIC/LMICN/
MICD1
PGA
LMICP
A BEEP pin input can also be amplified or muted by a PGA, up
to 32 dB in Register 16392 (0x4008), digital microphone and analog
beep control. The beep input must be enabled in Register 16400
(0x4010), microphone bias control and beep enable.
LEFT
ADC
DECIMATORS
CM
RMIC/RMICN/
MICD2
Microphone Bias
The MICBIAS pin provides a voltage reference for electret
microphones. Register 16400 (0x4010), microphone bias
control and beep enable, sets the operation mode of this pin.
RIGHT
ADC
CM
08313-029
PGA
RMICP
Example Configurations
Figure 31. Record Signal Path Diagram
TO DECIMATORS
LMIC/LMICN/
MICD1
The ADAU1381 can be configured for three types of microphone
inputs: single-ended, differential, or digital. The LMIC/LMICN/
MICD1 and RMIC/RMICN/MICD2 pins encompass all of these
configurations. LMICP and RMICP are used only during
differential configurations (see Figure 31, the record signal path
diagram).
Each analog input has individual gain controls (boost or cut). These
signals are routed to their respective right or left channel ADC.
PGA
LMICP
CM
TO DECIMATORS
RMIC/RMICN/
MICD2
PGA
RMICP
08313-030
INPUT SIGNAL PATH
CM
Analog Microphone Inputs
For differential inputs, RMICN and RMICP denote the negative
and positive input for the right channel, respectively. LMICN
and LMICP denote the negative and positive input for the left
channel, respectively.
Figure 32. Stereo Digital Microphone Input Configuration
LMIC/LMICN/
MICD1
PGA
LMICP
LMIC and RMIC inputs are single-ended line inputs. Together,
they can be used as a stereo single-ended input.
TO LEFT
ADC
CM
RMIC/RMICN/
MICD2
When a digital PDM microphone connected to the MICD1 or
MICD2 pin is used, Register 16392 (0x4008), digital microphone
and analog beep control, must be set appropriately to enable the
microphone input of choice. The MCKO output clock provides
the clock for the microphone and must be set accordingly in
Register 16384 (0x4000), clock control, depending on the
streaming PDM rate of the microphone.
The digital microphone signal bypasses the ADCs and is routed
directly into the decimation filters. The digital microphone and
ADCs share these decimation filters; therefore, both cannot be
used simultaneously.
Rev. B | Page 30 of 84
PGA
RMICP
TO RIGHT
ADC
CM
Figure 33. Single-Ended Input Configuration
08313-031
Digital Microphone Inputs
ADAU1381
Digital ADC Volume Control
LMIC/LMICN/
MICD1
PGA
LMICP
The ADC output (digital input) volume can be adjusted in
Register 16410 (0x401A), left ADC attenuator, Bits[7:0], left ADC
digital attenuator, for the left channel digital volume control and
in Register 16411 (0x401B), right ADC attenuator, Bits[7:0], right
ADC digital attenuator, for right channel digital volume control.
TO LEFT
ADC
CM
RMIC/RMICN/
MICD2
High-Pass Filter
CM
A high-pass filter is used in the ADC path to remove dc offsets
and can be selected in Register 16409 (0x4019), ADC control,
Bit 5, high-pass filter select, where it can be enabled or disabled.
08313-032
PGA
RMICP
TO RIGHT
ADC
Figure 34. Differential Input Configuration
DIGITAL DUAL-BAND AUTOMATIC LEVEL
CONTROL (ALC)
ANALOG-TO-DIGITAL CONVERTERS
The ADAU1381 uses two 24-bit Σ-Δ analog-to-digital converters
(ADCs) with selectable oversampling rates of either 64× or 128×.
The full-scale input to the ADCs depends on AVDD1. At 3.3 V,
the full-scale input level is 1.0 V rms. Inputs greater than the
full-scale value result in clipping and distortion.
The ADAU1381 includes an automatic level control (ALC). The
ALC adjusts the input gain continuously for a varying input signal
as dictated by the user-defined ALC settings. This allows the input
recording level to remain constant. Although this functionality
relates mainly to the record signal path, it is implemented digitally
in the sound engine.
Rev. B | Page 31 of 84
ADAU1381
PLAYBACK SIGNAL PATH
LEFT PLAYBACK
MIXER
beep signal. The mixer can be controlled in Register 16415
(0x401F), playback mono mixer control.
LINE OUT
AMPLIFIER
LEFT
DAC
AOUTL
LEFT
PLAYBACK
BEEP GAIN
MONO
PLAYBACK
BEEP GAIN
BEEP FROM
RECORD PGA
The drivers are low noise, Class AB mono amplifiers designed to
drive 8 Ω, 400 mW speakers. The output is differential and does
not require external capacitors. The gain settings for the speaker
drivers can be set in Register 16423 (0x4027), playback speaker
output control. In this register, the drivers can be set for any of
the four gain settings: 0 dB, 2 dB, 4 dB, or 6 dB. Additionally,
the speaker driver can be muted or powered down completely.
MONO
OUTPUT
GAIN
MONO
PLAYBACK
MIXER
SPP
RIGHT
PLAYBACK
BEEP GAIN
–1
SPN
MONO OUTPUT
INVERTER
RIGHT
DAC
08313-033
AOUTR
RIGHT PLAYBACK LINE OUT
MIXER
AMPLIFIER
Figure 35. Playback Signal Path Diagram
OUTPUT SIGNAL PATHS
The outputs of the ADAU1381 include a left and right line output
and speaker driver. The beep input signal can be mixed into any
of these outputs, with separate gain control for each path.
DIGITAL-TO-ANALOG CONVERTERS
The ADAU1381 uses two 24-bit Σ-Δ digital-to-analog converters
(DACs) with selectable oversampling rates of 64× or 128×. The
full-scale output of the DACs depends on AVDD1. At 3.3 V, the
full-scale output level is 1.0 V rms.
For pop and click suppression, an internal precharge sequence with
output gating/enabling occurs after the mono driver is enabled.
The sequence lasts for 8 ms, and then the internal mute signal
rising edge occurs (see Figure 36 for the power-up sequence
timing diagram).
The power-down sequence is essentially the reverse of the startup sequence, as depicted in Figure 37.
SPEAKER
OUTPUT
ENABLE
MONO
OUTPUT
MUTE
4ms
SPP
HIGH-Z
SPN
HIGH-Z
4ms
VCM
VCM
Digital DAC Volume Control
A de-emphasis filter is used in the DAC path to remove high
frequency noise in an FM system. This filter can be enabled or
disabled in Register 16426 (0x402A), DAC control.