19-5159; Rev 1; 12/10
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Features
The MAX1358B smart data-acquisition system (DAS) is
based on a 16-bit, sigma-delta analog-to-digital converter
(ADC) and system-support functionality for a microprocessor (µP)-based system. This device integrates
an ADC, DACs, operational amplifiers, internal selectable-voltage reference, temperature sensors, analog
switches, a 32kHz oscillator, a real-time clock (RTC)
with alarm, a high-frequency-locked loop (FLL) clock,
four user-programmable I/Os, an interrupt generator,
and 1.8V and 2.7V voltage monitors in a single chip.
The MAX1358B has dual 10:1 differential input multiplexers (muxes) that accept signal levels from 0 to AVDD. An
on-chip 1x to 8x programmable-gain amplifier (PGA)
allows measuring low-level signals and reduces external
circuitry required.
o +1.8V to +3.6V Single-Supply Operation
o Multichannel, 16-Bit, Sigma-Delta ADC
10sps to 477sps Programmable Conversion Rate
Self- and System Offset and Gain Calibration
PGA with Gains of 1, 2, 4, or 8
Unipolar and Bipolar Modes
10-Input Differential Multiplexer
o 10-Bit Force-Sense DACs
o Uncommitted Op Amps
o Dual SPDT and SPST Analog Switches
o Selectable References
1.25V, 2.048V, and 2.5V
o Internal Charge Pump
o System Support
RTC and Alarm Register
Internal/External Temperature Sensor
Internal Oscillator with Clock Output
User-Programmable I/O and Interrupt Generator
VDD Monitors
o SPI/QSPI/MICROWIRE, 4-Wire Serial Interface
o Space-Saving (6mm x 6mm x 0.8mm), 40-Pin
TQFN Package
TEMP RANGE
0°C to +70°C
-40°C to +85°C
IN1-
IN1+
AVDD
SWB
Industrial Control
FBB
OUTB
TOP VIEW
SWA
Pin Configuration
Electrochemical and Optical Sensors
Medical Instruments
PIN-PACKAGE
40 TQFN-EP*
40 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
FBA
Battery-Powered and Portable Devices
PART
MAX1358BCTL+
MAX1358BETL+
OUTA
Applications
Ordering Information
AGND
The MAX1358B operates from a single +1.8V to +3.6V
supply and consumes only 1.15mA in normal mode and
only 3µA in sleep mode. The MAX1358B has two DACs
with one uncommitted op amp.
The serial interface is compatible with either SPI™/QSPI™
or MICROWIRE™, and is used to power up, configure,
and check the status of all functional blocks.
The MAX1358B is available in a space-saving, 40-pin
TQFN package and is specified over the commercial
(0°C to +70°C) and the extended (-40°C to +85°C) temperature ranges.
30 29 28 27 26 25 24 23 22 21
Data-Acquisition Systems
31
20
32
19
SNC2
REF
33
18
SCM2
REG
34
17
SNO2
CF-
35
16
SNC1
CF+
36
15
SCM1
CPOUT
37
14
SNO1
DVDD
38
13
32KIN
DGND
39
12
32KOUT
UPIO1
40
11
RESET
*EXPOSED PAD.
MAX1358B
*EP
UPIO3
UPIO4
6
7
8
9
10
CLK32K
CLK
5
INT
4
CS
3
DIN
2
SCLK
1
UPIO2
+
DOUT
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
OUT1
AIN2
AIN1
TQFN
________________________________________________________________ Maxim Integrated Products
1
For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX1358B
General Description
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ABSOLUTE MAXIMUM RATINGS
Continuous Current Into Any Pin.........................................50mA
Continuous Power Dissipation (TA = +70°C)
40-Pin TQFN (derate 25.6mW/°C above +70°C) ....2051.3mW
Operating Temperature Range
MAX1358BCTL+ .................................................0°C to +70°C
MAX1358BETL+ ..............................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (reflow) .......................................+260°C
Lead Temperature (soldering, 10s) .................................+300°C
AVDD to AGND .........................................................-0.3V to +4V
DVDD to DGND.........................................................-0.3V to +4V
AVDD to DVDD ............................................................-4V to +4V
AGND to DGND.....................................................-0.3V to +0.3V
CLK32K to DGND ....................................-0.3V to (DVDD + 0.3V)
UPIO_ to DGND........................................................-0.3V to +4V
Digital Inputs to DGND ............................................-0.3V to +4V
Analog Inputs to AGND ...........................-0.3V to (AVDD + 0.3V)
Digital Output to DGND…........................-0.3V to (DVDD + 0.3V)
Analog Outputs to AGND.........................-0.3V to (AVDD + 0.3V)
CPOUT........................................................(DVDD - 0.3V) to +4V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
ADC DC ACCURACY
SYMBOL
CONDITIONS
MIN
Noise-Free Resolution
Data rate = 10sps, PGA gain = 2;
data rate = 10sps to 60sps, PGA gain = 1;
no missing codes, Table 1 (Note 2)
16
Conversion Rate
No missing codes, Table 1
10
TYP
477
No missing codes
Table 1
Integral Nonlinearity
Unipolar mode, AVDD = 3V,
PGA gain = 1, data rate = 40sps
±0.0046
Uncalibrated
Unipolar Offset Error (Note 3) or
Bipolar Zero Error (Note 2, 3)
%FSR
±0.003
Bipolar
1
Unipolar
1
%FSR
µV/°C
Uncalibrated
Gain Error (Notes 3, 5)
PGA = 1, calibrated, data rate = 10sps
Gain-Error Temperature
Coefficient
DC Positive Power-Supply
Rejection Ratio
sps
±1.0
PGA gain = 1, calibrated,
TA = +25°C, data rate = 10sps
Unipolar Offset-Error or Bipolar
Zero-Error Temperature Drift
(Note 4)
UNITS
Bits
Output Noise
INL
MAX
±0.6
±0.003
%FSR
(Notes 4, 6)
2
ppm/ °C
PSRR
PGA gain = 1, unipolar mode, measured by
full-scale error with AVDD = 1.8V to 3.6V
85
dB
CMRR
PGA gain = 1, unipolar mode
85
dB
ADC ANALOG INPUTS (AIN1, AIN2)
DC Input Common-Mode
Rejection Ratio
2
_______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Normal-Mode 60Hz Rejection
Ratio
PGA gain = 1, unipolar mode, data rate =
40sps (Note 2)
100
dB
Normal-Mode 50Hz Rejection
Ratio
Data rate = 10sps or 40sps, PGA gain = 1,
unipolar mode (Note 2)
100
dB
Absolute Input Range
VAGND
AVDD
Unipolar mode
-0.05/
Gain
VREF/
Gain
Bipolar mode
-VREF/
Gain
VREF/
Gain
Differential Input Range
V
DC Input Current (Note 7)
Input Sampling Capacitance
Input Sampling Rate
V
ADC not in measurement mode, mux
enabled, TA ≤ +55°C, inputs = +0.1V to
(AVDD - 0.1V)
±1
TA = +85°C
±5
nA
CIN
5
pF
fSAMPLE
21.94
kHz
External Source Impedance at Input
Table 3
FORCE-SENSE DAC (RL = 10kΩ and CL = 200pF, FBA = OUTA, unless otherwise noted)
Resolution
Guaranteed monotonic
10
Bits
Differential Nonlinearity
DNL
Code 3D hex to 3FF hex
±1
LSB
Integral Nonlinearity
INL
Code 3D hex to 3FF hex
±4
LSB
Reference to code 52 hex
±20
mV
Offset Error
Offset-Error Tempco
5
Gain Error
Excludes offset and voltage reference error
Gain-Error Tempco
Excludes offset and reference drift
Input Leakage Current at SWA/B
Switches open (Notes 7, 8)
Input Leakage Current at FBA/B
VFBA = +0.3V to
(AVDD - 0.3V)
(Note 7)
5.6
TA = -40°C to +85°C
±1
nA
±1
nA
±600
TA = 0°C to +50°C
±400
DAC buffer disabled (Note 7)
Input Common-Mode Voltage
At FBA
Line Regulation
AVDD = +1.8V to +3.6V, TA = +25°C
Load Regulation
IOUT = ±2mA, CL = 1000pF (Note 2)
0
40
VAGND
LSB
ppm/°C
TA = 0°C to +70°C
DAC Output Buffer Leakage
Current
Output Voltage Range
µV/°C
±5
pA
±75
nA
AVDD 0.35
V
175
µV/V
0.5
µV/µA
AVDD
V
_______________________________________________________________________________________
3
MAX1358B
ELECTRICAL CHARACTERISTICS (continued)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output Slew Rate
52 hex to 3FF hex code swing rising or
falling, RL = 10kΩ, CL = 100pF
50
V/ms
Output-Voltage Settling Time
10% to 90% rising or falling to ±0.5 LSB
65
µs
f = 0.1Hz to
10Hz
40
f = 10Hz to
10kHz
100
Referred to FBA,
excludes reference noise
Input-Voltage Noise
Output Short-Circuit Current
µVP-P
OUTA shorted to AGND
20
OUTA shorted to AVDD
18
mA
Input-Output SWA/SWB
Switch Resistance
Between SW_ and OUT_, HFCLK enabled
(Note 2)
SWA/SWB Switch Turn-On/Off
Time
HFCLK enabled
100
ns
Power-On Time
Excluding reference
12
µs
150
Ω
EXTERNAL REFERENCE (REF)
Input Voltage Range
VAGND
Input Resistance
DAC on, internal REF and ADC off
DC Input Leakage Current
Internal REF, DAC, and ADC off (Note 7)
AVDD
2.5
V
MΩ
100
nA
INTERNAL VOLTAGE REFERENCE (CREF = 4.7µF)
Reference Output Voltage
VREF
Output-Voltage Temperature
Coefficient (Note 7)
TC
Output Short-Circuit Current
IRSC
AVDD ≥ +1.8V,
TA = +25°C
1.213
1.25
1.288
AVDD ≥ +2.2V,
TA = +25°C
1.987
2.048
2.109
AVDD ≥ +2.7V,
TA = +25°C
2.425
2.5
2.575
TA = -40°C to +85°C
25
TA = 0°C to +70°C
13
4
ppm/oC
REF shorted to AGND
65
mA
REF shorted to AVDD
90
µA
25
µV/V
Line Regulation
Load Regulation
V
TA = +25°C,
VREF = 1.25V
ISOURCE = 0 to 500µA
ISINK = 0 to 50µA
1.2
1.7
_______________________________________________________________________________________
µV/µA
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Long-Term Stability
CONDITIONS
MIN
(Note 9)
TYP
MAX
UNITS
ppm/
1000hrs
150
f = 0.1Hz to 10Hz, AVDD = 3V
50
f = 10Hz to 10kHz, AVDD = 3V
200
Buffer only, settle to 0.1% of final value
100
µs
Temperature Measurement
Resolution
10sps
0.11
°C/LSB
Internal Temperature-Sensor
Measurement Error (Note 10)
External voltage
reference, twocurrent method
Output Noise Voltage
Turn-On Settling Time
µVP-P
TEMPERATURE SENSOR
External Temperature-Sensor
Measurement Error (Note 11)
±0.5
TA = 0°C to +50°C
°C
±1
TA = -40oC to +85°C
TA = +25°C
±0.5
TA = 0°C to +50°C
±0.5
°C
±1.0
TA = -40°C to +85°C
Temperature Measurement Noise
0.18
°CRMS
Temperature Measurement
Power-Supply Rejection Ratio
0.2
°C/V
OP AMP
Input Offset Voltage
VOS
±1
VCM = 0.5V
Offset-Error Tempco
IN1+
IBIAS
±1
TA = 0°C to +70°C
4
±300
TA = 0°C to +50°C
2
±200
0.025
±1
20
±600
TA = -40°C to +85°C
IN1-
TA = 0°C to +70°C
±400
TA = 0°C to +50°C
Input Offset Current
IOS
Input Common-Mode Voltage
Range
VIN1_ = +0.3V to (AVDD - 0.3V) (Note 7)
CMVR
0
0 ≤ VCM ≤ 75mV
Common-Mode Rejection Ratio
CMRR
75mV < VCM ≤ AVDD - 0.5V, TA = +25°C
AVDD - 0.5V ≤ VCM ≤ AVDD - 0.35V
mV
µV/oC
0.006
TA = -40°C to +85°C
Input Bias Current (Note 7)
±15
6.2
nA
pA
nA
pA
±1
nA
AVDD 0.35
V
60
60
75
dB
75
_______________________________________________________________________________________
5
MAX1358B
ELECTRICAL CHARACTERISTICS (continued)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
Power-Supply Rejection Ratio
PSRR
AVDD = +1.8V to +3.6V, TA = +25°C
Large-Signal Voltage Gain
AVOL
100mV ≤ VOUT_ ≤ AVDD - 100mV (Note 12)
Sourcing
Output-Voltage Drop (Note 2)
GBW
Phase Margin
Output Slew Rate
SR
Output Short-Circuit Current
76.5
100
90
116
MAX
UNITS
dB
dB
ISOURCE = 10µA
0.005
ISOURCE = 50µA
0.025
ISOURCE = 100µA
0.05
ISOURCE = 500µA
0.25
0.5
ISINK = 10µA
0.005
ISINK = 50µA
0.025
ISINK = 100µA
0.05
ISINK = 500µA
0.25
ISINK = 2mA
0.5
V
Unity-gain configuration, CL = 1nF
80
kHz
Unity-gain configuration, CL = 1nF (Note 12)
60
Degrees
0.05
V/µs
CL = 200pF
Unity-gain
configuration
Input-Voltage Noise
TYP
ISOURCE = 2mA
ΔVOUT
Sinking
Gain Bandwidth Product
MIN
f = 0.1Hz to 10Hz
50
f = 10Hz to 10kHz
100
VOUT_ shorted to AGND
20
VOUT_ shorted to AVDD
18
Power-On Time
µVP-P
mA
12
µs
SPDT SWITCHES (SNO_, SNC_, SCM_, HFCLK enabled)
On-Resistance (Note 2)
RON
VSCM_ = 0V
TA = 0°C to +50°C
45
VSCM_ = 0.5V
TA = 0°C to +50°C
50
VSCM_ = 0.5V to AVDD TA = -40°C to +85°C
150
VSNO_, VSNC_ = +0.5V, TA = -40°C to +85°C
ISNO_(OFF)
+1.5V; VSCM_ = +1.5V, TA = 0°C to +70°C
ISNC_(OFF)
+0.5V (Note 7)
TA = 0°C to +50°C
±600
SCM_ Off-Leakage Current
VSNO_, VSNC_ = +0.5V, TA = -40°C to +85°C
ISCM_(OFF) +1.5V; VSCM_ = +1.5V, TA = 0°C to +70°C
+0.5V (Note 7)
TA = 0°C to +50°C
±1.2
SCM_ On-Leakage Current
VSNO_, VSNC_ = +0.5V, TA = -40°C to +85°C
+1.5V, or unconnected;
TA = 0°C to +70°C
VSCM_ = +1.5V, +0.5V
TA = 0°C to +50°C
(Note 7)
SNO_, SNC_ Off-Leakage Current
ISCM_(ON)
Input Voltage Range
Turn-On/Off Time
6
±1
±400
Break-before-make
nA
pA
±2
nA
±0.8
±2
±1.2
nA
±0.8
VAGND
tON/tOFF
Ω
AVDD
100
_______________________________________________________________________________________
V
ns
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
SNO_, SNC_, or SCM_ = AVDD or AGND;
switch connected to enabled mux input
Input Capacitance
TYP
MAX
2.5
UNITS
pF
CHARGE PUMP
Maximum Output Current
Output Voltage
IOUT
10
No load
3.2
IOUT = 10mA
3.0
Output-Voltage Ripple
IOUT = 10mA, excluding ESR of external
capacitor (Note 2)
Load Regulation
IOUT = 10mA, excluding ESR of external
capacitor
REG Input Voltage Range
Internal linear regulator disabled (Note 2)
REG Input Current
Linear regulator off, charge pump off
CPOUT Input Voltage Range
Charge pump disabled
CPOUT Input Leakage Current
Charge pump disabled
mA
3.3
15
1.6
3.6
50
mVP-P
20
mV/mA
1.8
3
1.8
V
V
nA
3.6
2
V
nA
SIGNAL-DETECT COMPARATOR
Differential Input-Detection
Threshold Voltage
TSEL[2:0] = 0 hex
0
TSEL[2:0] = 4 hex
50
TSEL[2:0] = 5 hex
100
TSEL[2:0] = 6 hex
150
TSEL[2:0] = 7 hex
200
Differential Input-Detection
Threshold Error
mV
±10
Common-Mode Input Voltage
Range
AVDD
VAGND
Turn-On Time
mV
45
V
µs
VOLTAGE MONITORS
DVDD Monitor Supply Voltage
Range
For valid reset (Note 7)
Trip Threshold (DVDD Falling)
1.80
DVDD Monitor Timeout Reset
Period
DVDD Monitor Hysteresis
1.4
1.85
1.5
HYSE bit set to logic 1
225
HYSE bit set to logic 0
40
3.6
V
1.95
V
s
mV
_______________________________________________________________________________________
7
MAX1358B
ELECTRICAL CHARACTERISTICS (continued)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
DVDD Monitor Turn-On Time
TYP
MAX
5
CPOUT Monitor Supply Voltage
Range
(Note 7)
CPOUT Monitor Trip Threshold
1.4
2.7
ms
3.6
2.8
UNITS
2.9
V
V
CPOUT Monitor Hysteresis
35
mV
CPOUT Monitor Turn-On Time
5
ms
Internal Power-On Reset Voltage
1.7
V
32kHz OSCILLATOR (32KIN, 32KOUT)
Clock Frequency
DVDD = 2.7V
Stability
DVDD = 1.8V to 3.6V, excluding crystal
Oscillator Startup Time
Crystal Load Capacitance
32.768
kHz
25
ppm
1500
ms
6
pF
32.768
kHz
LOW-FREQUENCY CLOCK INPUT/OUTPUT (CLK32K)
Output Clock Frequency
Absolute Input to Output Clock
Jitter
Cycle to cycle
5
ns
Input to Output Rise/Fall Time
10% to 90%, 30pF load
5
ns
Input Duty Cycle
40
Output Duty Cycle
60
54
%
%
HIGH-FREQUENCY CLOCK OUTPUT (CLK)
FLL Output Clock Frequency
Absolute Clock Jitter
Rise and Fall Time
tR/tF
Duty Cycle
Uncalibrated CLK Frequency
Error
fOUT = fFLL
4.8660
4.9152
4.9644
fOUT = fFLL/2, power-up default
2.4330
2.4576
2.4822
fOUT = fFLL/4
1.2165
1.2288
1.2411
fOUT = fFLL/8
608.25
614.4
620.54
Cycle to cycle, FLL off
0.1
Cycle to cycle, FLL on
0.5
10% to 90%, 30pF load
kHz
ns
10
fOUT = 4.9152MHz
40
60
fOUT = 2.4576MHz, 1.2288MHz, 614.4kHz
45
55
±35
FLL calibration not performed
MHz
ns
%
%
DIGITAL INPUTS (SCLK, DIN, CS, UPIO_, CLK32K)
Input High Voltage
VIH
Input Low Voltage
VIL
8
0.7 x
DVDD
_______________________________________________________________________________________
V
0.3 x
DVDD
V
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
DVDD supply voltage
UPIO_ Input High Voltage
CPOUT supply voltage
MIN
TYP
V
0.3 x
DVDD
UPIO_ Input Low Voltage
VHYS
IIN
VCPOUT
DVDD = 3.0V
200
±0.01
VIN = VDGND or DVDD (Note 7)
Input Capacitance
VIN = VDGND or DVDD
UPIO_ Input Current (Note 2)
VIN = DVDD or VCPOUT or 0V,
pullup disabled
VIN = 0V, pullup enabled, unconnected
UPIO_ inputs are pulled up to DVDD or
CPOUT with pullup enabled (Note 2)
mV
±100
4
±0.01
VIN = DVDD or VCPOUT, pullup enabled
UPIO_ Pullup Current
V
0.3 x
CPOUT supply voltage
Input Current
UNITS
0.7 x
VCPOUT
DVDD supply voltage
Input Hysteresis
MAX
0.7 x
DVDD
1
1
0.1
2
nA
pF
µA
5
µA
0.4
V
DIGITAL OUTPUTS (DOUT, RESET, UPIO_, CLK32K, INT, CLK)
Output Low Voltage
VOL
ISINK = 1mA
Output High Voltage
VOH
ISOURCE = 500µA
DOUT Three-State Leakage
Current
DOUT Three-State Output
Capacitance
RESET Output Low Voltage
UPIO_ Output High Voltage
V
IL
±0.01
COUT
4.5
VOL
RESET Output Leakage Current
UPIO_ Output Low Voltage
0.8 x
DVDD
VOL
VOH
±1
µA
pF
ISINK = 1mA
0.4
V
Open-drain output, RESET deasserted
(Note 7)
0.1
µA
ISINK = 1mA, UPIO_ referenced to DVDD
0.4
ISINK = 4mA, UPIO_ referenced to CPOUT
0.4
ISOURCE = 500µA, UPIO_ referenced to
DVDD
ISOURCE = 4mA, UPIO_ referenced to
CPOUT
0.8 x
DVDD
V
V
VCPOUT
- 0.4
POWER REQUIREMENT
Analog Supply Voltage Range
AVDD
1.8
3.6
V
Digital Supply Voltage Range
DVDD
1.8
3.6
V
_______________________________________________________________________________________
9
MAX1358B
ELECTRICAL CHARACTERISTICS (continued)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = DVDD = +1.8V to +3.6V, VREF = +1.25V, external reference, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT =
10µF, 10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
IMAX
Total Supply Current (Note 2)
INORMAL
Sleep-Mode Supply Current
(IAVDD + IDVDD)
Shutdown Supply Current
(IAVDD + IDVDD)
CONDITIONS
Everything on,
charge pump
unloaded, no digital
pins, sinking/sourcing
current, e.g., RST,
UPIO_, and CLK32K,
max internal tempsensor current, clock
output buffers
unloaded, ADC at
477sps
ISLEEP
TA = +25°C
ISHDN
TYP
MAX
AVDD = DVDD = 3.6V
1.2
2.0
AVDD = DVDD = 2.7V
1.15
1.4
1.15
1.5
3.0
5.2
All off
UNITS
mA
All on except charge pump and temp
sensor, ADC at 477sps, CLK output buffer
enabled, clock output buffers unloaded
TA = -40°C to +85°C
MIN
AVDD = DVDD = 2.7V
AVDD = DVDD = 3.6V
6.7
AVDD = DVDD = 2.7V
3.0
AVDD = DVDD = 3.6V
4.5
TA = -40°C to +85°C
TA = +25°C
2.5
1.2
µA
µA
Note 1: Devices are production tested at TA = room temperature. Specifications to TA = -40°C and TA = +85°C are guaranteed by design.
Note 2: Guaranteed by design or characterization.
Note 3: The offset and gain errors are corrected by self-calibration or system calibration. For accurate calibrations, perform calibration at the lowest rate. The calibration error is therefore in the order of peak-to-peak noise for the selected rate.
Note 4: Eliminate drift errors by recalibration at the new temperature.
Note 5: The gain error excludes reference error, offset error (unipolar), and zero error (bipolar).
Note 6: Gain-error drift does not include unipolar-offset drift or bipolar zero-error drift. It is effectively the drift of the part if zeroscale error is removed.
Note 7: These specifications are obtained from characterization during design or from initial product evaluation. Not production
tested or guaranteed.
Note 8: VOUTA = +0.5V or +1.5V, VSWA = +1.5V or +0.5V, TA = 0°C to +50°C.
Note 9: Long-term stability is characterized using five to six parts. The bandgaps are turned on for 1000hrs at room temperature
with the parts running continuously. Daily measurements are taken and any obvious outlying data points are discarded.
Note 10: Temperature error is the difference in the calculated temperature using the internal circuit vs. measurements made using
precision external voltage and current meters. The same diode and diode equation are used for both measurements.
Note 11: All the stated temperature accuracies assume that 1) the external diode characteristic is precisely known (i.e., ideal) and
2) the ADC reference voltage is exactly equal to 1.25V. Any variations to this known reference characteristic and voltage
caused by temperature, loading, or power supply results in errors in the temperature measurement. The actual temperature calculation is performed externally by the µC.
Note 12: Values based on simulation results and are not production tested or guaranteed.
10
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
Table 1. Output Noise (Notes 13 and 14)
OUTPUT NOISE (µVRMS)
RATE (sps)
10
GAIN = 1
1.75
GAIN = 2
1.75
GAIN = 4
1.75
GAIN = 8
1.75
40
2.92
2.92
2.92
2.92
50
3.23
3.23
3.23
3.23
60
3.60
3.60
3.60
3.60
200
56.06
56.06
56.06
56.06
240
102.36
102.36
102.36
102.36
400
587.06
587.06
587.06
587.06
477
951.07
951.07
951.07
951.07
Note 13: VREF = +1.25V, bipolar mode, VIN = 1.24912V, PGA gain = 1, TA = +25°C.
Note 14: Assume ±3 sigma peak-to-peak variation; noise-free resolution means no code flicker at given bits’ LSB.
Table 2. Peak-to-Peak Resolution
PEAK-TO-PEAK RESOLUTION (BITS)
RATE (sps)
GAIN = 1
GAIN = 2
GAIN = 4
GAIN = 8
10
17.57
16.57
15.57
14.57
40
16.83
15.83
14.83
13.83
50
16.68
15.68
14.68
13.68
60
16.53
15.53
14.53
13.53
200
12.57
11.57
10.57
9.57
240
11.70
10.70
9.70
8.70
400
9.18
8.18
7.18
6.18
477
8.48
7.48
6.48
5.48
Table 3. Maximum External Source Impedance Without 16-Bit Gain Error
PARAMETER
Resistance (kΩ)
EXTERNAL CAPACITANCE (pF)
0 (Note 15)
50
100
500
1000
5000
350
60
30
10
4
1
Note 15: 2pF parasitic capacitance is assumed, which represents pad and any other parasitic capacitance.
______________________________________________________________________________________
11
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
TIMING CHARACTERISTICS (Figures 1 and 19)
(AVDD = DVDD = +1.8V to +3.6V, external VREF = +1.25V, fCLK32K = 32.768kHz (external clock), CREG = 10µF, CCPOUT = 10µF,
10µF between CF+ and CF-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
10
MHz
SCLK Operating Frequency
fSCLK
0
SCLK Cycle Time
tCYC
100
ns
SCLK Pulse-Width High
tCH
40
ns
SCLK Pulse-Width Low
tCL
40
ns
DIN to SCLK Setup
tDS
30
ns
DIN to SCLK Hold
tDH
SCLK Fall to DOUT Valid
tDO
CL = 50pF, Figure 2
40
ns
CS Fall to DOUT Enable
tDV
CL = 50pF, Figure 2
48
ns
tTR
CL = 50pF, Figure 2
48
ns
CS Rise to DOUT Disable
0
ns
CS to SCLK Rise Setup
tCSS
20
ns
CS to SCLK Rise Hold
tCSH
0
ns
DVDD Monitor Timeout Period
tDSLP
(Note 16)
1.5
s
Wake-Up (WU) Pulse Width
tWU
Minimum pulse width required to detect a
wake-up event
1
µs
Shutdown Delay
tDPU
The delay for SHDN to go high after a valid
wake-up event
1
µs
HFCLK Turn-On Time (Note 2)
CRDY to INT Delay
tDFON
tDFI
The turn-on time for the high-frequency
clock and FLL (FLLE = 1) (Note 17)
10
ms
If FLLE = 0, the turn-on time for the highfrequency clock (Notes 7, 18)
10
µs
The delay for CRDY to go low after the
HFCLK clock output has been enabled
(Note 19)
7.82
ms
HFCLK Disable Delay
tDFOF
The delay after a shutdown command has
asserted and before HFCLK is disabled
(Note 20)
1.95
ms
SHDN Assertion Delay
tDPD
(Note 21)
2.93
ms
Note 16: The delay for the sleep voltage monitor output, RESET, to go high after VDD rises above the reset threshold. This is largely
driven by the startup of the 32kHz oscillator.
Note 17: FLLE is gated by an AND function with three inputs—the external RESET signal, the internal DVDD monitor output, and the
external SHDN signal. The time delay is timed from the internal LOVDD going high or the external RESET going high,
whichever happens later. HFCLK always starts in the low state.
Note 18: If FLLE = 0, the internal signal CRDY is not generated by the FLL block and INT or INT is deasserted.
Note 19: CRDY is used as an interrupt signal to inform the µC that the high-frequency clock has started. Only valid if FLLE = 1.
Note 20: tDFOF gives the µC time to clean up and go into sleep-override mode properly.
Note 21: tDPD is greater than the HFCLK delay to clean up before losing power.
12
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
CS
tCSH
tCH
tCYC
tCSH
tCSS
tCL
SCLK
tDS
tDH
DIN
tDV
tDO
tTR
DOUT
Figure 1. Detailed Serial-Interface Timing
DVDD
6kΩ
DOUT
DOUT
6kΩ
CLOAD = 50pF
a) FOR ENABLE, HIGH IMPEDANCE
TO VOH AND VOL TO VOH
FOR DISABLE, VOH TO HIGH IMPEDANCE
CLOAD = 50pF
b) FOR ENABLE, HIGH IMPEDANCE
TO VOL AND VOH TO VOL
FOR DISABLE, VOL TO HIGH IMPEDANCE
Figure 2. DOUT Enable and Disable Time Load Circuits
Typical Operating Characteristics
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
ALL ON WITH ADC AT 477sps AND
MAXIMUM INTERNAL TEMP-SENSOR
CURRENT SETTING
0.8
IDVDD
0.7
IAVDD
0.6
10.000
SUPPLY CURRENT (µA)
SUPPLY CURRENT (mA)
0.9
MAX1358B toc01
1.0
MAX1358B toc02
DVDD SUPPLY CURRENT
vs. DVDD SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SLEEP MODE
1.000
SLEEP MODE: ALL OFF EXCEPT
32kHz OSC, RTC, AND 1.8V MONITOR
SHUTDOWN MODE: ALL OFF
0.100
0.010
0.5
0.4
SHUTDOWN MODE
0.001
1.8
2.1
2.4
2.7
3.0
AVDD, DVDD (V)
3.3
3.6
1.8
2.1
2.4
2.7
3.0
3.3
3.6
DVDD (V)
______________________________________________________________________________________
13
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
SLEEP MODE
SHUTDOWN MODE
0.8
0.4
0.6
0
0.5
DVDD = 1.8V
2.0
DVDD = 3.0V
1.5
1.0
2.4
2.7
3.0
3.3
3.6
-15
10
35
85
60
-40
-15
10
35
60
TEMPERATURE (°C)
TEMPERATURE (°C)
DVDD SUPPLY CURRENT
vs. TEMPERATURE
AVDD SUPPLY CURRENT
vs. TEMPERATURE
AVDD SUPPLY CURRENT
vs. TEMPERATURE
0.55
0.51
DVDD = 3.0V
0.49
0.45
-15
10
35
DVDD = 1.8V
0.47
DVDD = 1.8V
85
60
-40
-15
10
35
0.40
DVDD = 3.0V
0.30
DVDD = 1.8V
-15
1.3
DVDD = 1.8V
-40
-15
10
35
TEMPERATURE (°C)
60
10
35
60
TEMPERATURE (°C)
85
2.60
OSCILLATOR FREQUENCY (MHz)
SUPPLY CURRENT (µA)
0.45
-40
DVDD = 3.0V
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
MAX1358B toc09
ALL OFF
2.55
FLL DISABLED
FLL ENABLED
2.50
2.45
2.40
2.35
2.30
-40
85
1.7
TEMPERATURE (°C)
0.50
0.20
2.1
0.5
85
60
AVDD SUPPLY CURRENT
vs. TEMPERATURE
0.25
SLEEP MODE: ALL OFF EXCEPT
32kHz OSC, RTC, AND 1.8V MONITOR
0.9
TEMPERATURE (°C)
0.35
2.5
MAX1358B toc10
DVDD = 3.0V
8
4
0.53
SUPPLY CURRENT (mA)
12
ALL ON WITH ADC AT 512sps AND
MAXIMUM INTERNAL TEMP-SENSOR
CURRENT SETTING
SUPPLY CURRENT (mA)
MAX1358B toc06
16
-40
-40
SUPPLY VOLTAGE (V)
MAX1358B toc08
2.1
0.5
MAX1358B toc07
1.8
ALL OFF
14
2.5
DVDD = 1.8V
20
0
DVDD = 3.0V
0.7
SLEEP MODE: ALL OFF EXCEPT
32kHz OSC, RTC, AND 1.8V MONITOR
SUPPLY CURRENT (mA)
1.2
0.8
ALL ON WITH ADC AT 512sps AND
MAXIMUM INTERNAL TEMP-SENSOR
CURRENT SETTING
0.9
3.0
MAX1358B toc04
SLEEP MODE: ALL OFF EXCEPT
32kHz OSC, RTC, AND 1.8V MONITOR
SHUTDOWN MODE: ALL OFF
SUPPLY CURRENT (mA)
SUPPLY CURRENT (µA)
1.0
MAX1358B toc03
2.0
1.6
DVDD SUPPLY CURRENT
vs. TEMPERATURE
DVDD SUPPLY CURRENT
vs. TEMPERATURE
MAX1358B toc05
AVDD SUPPLY CURRENT
vs. AVDD SUPPLY VOLTAGE
SUPPLY CURRENT (nA)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
-15
10
35
TEMPERATURE (°C)
______________________________________________________________________________________
60
85
85
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
2.40
2.35
FLL DISABLED
2.1
2.4
2.7
3.0
3.3
3.6
1.2492
1.8
3.0
3.3
3.6
MAX1358B toc13
-50
50
150
250
350
450
REFERENCE OUTPUT VOLTAGE
vs. TEMPERATURE
2.0488
2.4968
2.4966
2.4964
2.4962
50
1.250
1.249
1.248
1.247
1.246
VREF = 2.5V
150
250
350
450
550
2.4960
-50
50
VREF = 1.25V
150
250
350
450
OUTPUT CURRENT (µA)
OUTPUT CURRENT (µA)
REFERENCE OUTPUT VOLTAGE
vs. TEMPERATURE
REFERENCE OUTPUT VOLTAGE
vs. TEMPERATURE
2.046
2.044
-15
10
35
85
60
REFERENCE DRIFT (0˚C TO 50˚C)
2.497
VREF = 1.25V
BOX METHOD
OCCURRENCES
2.048
-40
MAX1358B toc18
2.050
550
1.245
TEMPERATURE (°C)
2.500
REFERENCE OUTPUT VOLTAGE (V)
MAX1358B toc17
2.052
2.494
2.491
2.488
VREF = 2.5V
VREF = 2.048V
2.485
-15
1.251
550
MAX1358B toc16
2.4970
VREF = 2.048V
REFERENCE OUTPUT VOLTAGE (V)
2.7
REFERENCE OUTPUT VOLTAGE
vs. OUTPUT CURRENT
2.0490
-40
2.4
REFERENCE OUTPUT VOLTAGE
vs. OUTPUT CURRENT
2.0492
2.042
2.1
OUTPUT CURRENT (µA)
MAX1358B toc14
REFERENCE OUTPUT VOLTAGE (V)
1.0
SUPPLY VOLTAGE (V)
2.0494
-50
1.2494
AVDD, DVDD SUPPLY VOLTAGE (V)
2.0496
2.0486
1.2496
VREF = 1.25V
CLK = 2.4576MHz
1.8
1.5
1.2498
REFERENCE OUTPUT VOLTAGE (V)
2.20
VREF = 2.048V
VREF = 1.25V
1.2500
MAX1358B toc18b
2.25
2.0
MAX1358B toc15
2.30
2.5
1.2502
REFERENCE OUTPUT VOLTAGE (V)
2.45
MAX1358B toc12
FLL ENABLED
2.50
VREF = 2.50V
50kI LOAD
REFERENCE OUTPUT VOLTAGE (V)
MAX1358B toc11
2.55
3.0
REFERENCE OUTPUT VOLTAGE (V)
INTERNAL OSCILLATOR FREQUENCY (MHz)
2.60
REFERENCE OUTPUT VOLTAGE
vs. OUTPUT CURRENT
REFERENCE OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
10
35
TEMPERATURE (°C)
60
85
-40
-15
10
35
TEMPERATURE (°C)
60
85
6
11
16
21
26
ABSOLUTE DRIFT (ppm/NC)
______________________________________________________________________________________
15
MAX1358B
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
REFERENCE NOISE DENSITY vs.
FREQUENCY
1000
VREF = 1.25V
0
-0.002
100
INL (LSB)
50µV/div
AC-COUPLED
ADC INL vs. OUTPUT CODE
0.002
MAX1358B toc20
MAX1358B toc19
MAX1358B toc21
REFERENCE VOLTAGE OUTPUT NOISE
(0.1Hz TO 10Hz)
NOISE (nV/√Hz)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
-0.004
VREF = 2.048V
UNIPOLAR MODE
GAIN = 1
60sps
-0.006
10
-0.008
0.001
-0.0044
-0.002
-0.0060
10k
20k
30k
40k
50k
60k
70k
VREF = 2.048V
UNIPOLAR MODE
GAIN = 1
60sps
-0.0024
-0.0021
-0.0020
2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6
-0.004
-0.005
0.0025
0.0020
0.0015
0.0010
0
-15
10
35
TEMPERATURE (NC)
16
0.0030
VREF = 1.25V
BIPOLAR MODE
GAIN = 1
60sps
0.0005
-0.006
-40
1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
ADC MAXIMUM INL vs. TEMPERATURE
-0.003
-0.007
VREF = 1.25V
BIPOLAR MODE
GAIN = 1
60sps
SUPPLY VOLTAGE (V)
ADC MAXIMUM INL (%)
-0.002
60
85
70k
-0.0022
MAX1358B toc25
VREF = 2.048V
UNIPOLAR MODE
GAIN = 1
60sps
-0.001
60k
-0.0023
ADC MAXIMUM INL vs. TEMPERATURE
0
50k
-0.0025
SUPPLY VOLTAGE (V)
OUTPUT CODE
40k
MAX1358B toc26
0
30k
ADC MAXIMUM INL vs.
SUPPLY VOLTAGE
-0.004
-0.005
20k
ADC MAXIMUM INL vs.
SUPPLY VOLTAGE
-0.0056
-0.003
10k
OUTPUT CODE
-0.0052
-0.001
0
FREQUENCY (Hz)
-0.0048
0
ADC MAXIMUM INL (%)
INL (LSB)
0.002
10,000
1000
MAX1358B toc24
0.003
ADC MAXIMUM INL (%)
AVDD = DVDD = 1.8V
VREF = 1.25V
BIPOLAR MODE
GAIN = 1
60sps
0.004
-0.0040
MAX1358B toc22
0.005
100
ADC MAXIMUM INL (%)
ADC INL vs. OUTPUT CODE
-0.010
10
MAX1358B toc23
1
1s/div
-40
-15
10
35
TEMPERATURE (NC)
______________________________________________________________________________________
60
85
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
-0.0015
-0.0020
-0.0025
-0.0030
-0.0035
MAX1358B toc28
AVDD = DVDD = 1.8V
VREF = 1.25V
BIPOLAR MODE
GAIN = 1
0.025
-0.0040
ADC MAXIMUM INL vs. PGA GAIN
0.010
0.020
0.015
0.010
AVDD = DVDD = 1.8V
VREF = 1.25V
BIPOLAR MODE
60sps
0.008
ADC MAXIMUM INL (%)
ADC MAXIMUM INL (%)
-0.0010
VREF = 1.25V
BIPOLAR MODE
GAIN = 1
60sps
ADC MAXIMUM INL (%)
-0.0005
0.030
MAX1358B toc27
0
ADC MAXIMUM vs.
OUTPUT DATA RATE
MAX1358B toc29
ADC MAXIMUM INL vs.
COMMON-MODE INPUT VOLTAGE
0.006
0.004
0.002
0.005
-0.0045
1.4
1.6
1.8
2.0
0
100
200
300
0
500
400
4
6
8
PGA GAIN
ADC OFFSET ERROR vs.
TEMPERATURE
ADC GAIN ERROR vs.
TEMPERATURE
ADC OFFSET ERROR vs.
SUPPLY VOLTAGE
0.006
VREF = 2.048V
UNIPOLAR MODE
GAIN = 1
60sps
0.005
ADC GAIN ERROR (%)
0
0.0035
0.004
0.003
0.002
0
-15
10
35
60
85
-40
-15
10
35
0.0010
0.0005
1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE (V)
ADC MUX INPUT DC CURRENT vs.
TEMPERATURE
0.0025
0.0020
0.0015
MAX1358B toc34
1000.00
100.00
INPUT CURRENT (nA)
0.0030
0.0015
TEMPERATURE (NC)
MAX1358B toc33
0.0035
0.0020
-0.0005
85
60
ADC GAIN ERROR vs.
SUPPLY VOLTAGE
VREF = 1.25V
UNIPOLAR MODE
GAIN = 1
60sps
0.0025
0
TEMPERATURE (NC)
0.0040
VREF = 1.25V
UNIPOLAR MODE
GAIN = 1
60sps
0.0030
0.001
-0.0005
GAIN ERROR (%FSR)
2
DATA RATE (sps)
0.0005
-40
0
COMMON-MODE VOLTAGE (V)
0.0010
-0.0010
0
2.2
VREF = 2.048V
UNIPOLAR MODE
GAIN = 1
60sps
0.0015
ADC OFFSET ERROR (%)
1.2
ADC CONVERTING
10.00
1.000
ADC OFF
0.100
0.0010
AIN1 = AVDD/2
MUX+ = AIN1
MUX- = AGND
0.010
0.0005
0
1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE (V)
MAX1358B toc32
0.0020
1.0
OFFSER ERROR (%FSR)
0.8
MAX1358B toc31
0.6
MAX1358B toc30
-0.0050
0.001
-40
-15
10
35
60
85
TEMPERATURE (NC)
______________________________________________________________________________________
17
MAX1358B
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
SW_ LEAKAGE CURRENT
vs. INPUT VOLTAGE
1.5
TA = +55°C
TA = +25°C
0.1
0
-0.1
0.5
TA = +25°C
-0.2
0
0.5
1.0
1.5
2.0
2.5
0
-0.1
0
0.5
1.0
1.5
2.0
-0.3
3.0
2.5
0
0.5
1.0
1.5
2.0
2.5
SNO_ LEAKAGE CURRENT
vs. INPUT VOLTAGE
SNC_ LEAKAGE CURRENT
vs. INPUT VOLTAGE
SCM_ LEAKAGE CURRENT
vs. INPUT VOLTAGE
0.10
0.20
MAX1358B toc38
TA = +85°C
0.05
0
SCM_ = AVDD/2
0.15
INPUT CURRENT (nA)
TA = +55°C
TA = +85°C
0.10
TA = +55°C
0.05
0
-0.05
TA = +25°C
-0.10
-0.20
2.0
2.5
3.0
0
0.5
1.0
1.5
2.0
3.0
2.5
0
0.5
0.5
MAX1358B toc41
TA = +85NC
0.4
0.3
TA = +55NC
2.0
AVDD = 1.8V
VREF = 1.25V
0.2
INL (LSB)
0.05
0
-0.05
1.5
DAC INL vs. OUTPUT CODE
0.20
0.15
1.0
VSCM_ (V)
VSNC_ (V)
IN1- LEAKAGE CURRENT
vs. INPUT VOLTAGE
0.10
TA = +25°C
-0.10
-0.15
1.5
TA = +55°C
0
-0.20
VSNO_ (V)
TA = +25NC
0.1
0
-0.1
-0.2
-0.10
-0.3
-0.15
-0.4
-0.20
-0.5
0
0.5
1.0
1.5
VIN1- (V)
2.0
2.5
3.0
3.0
0.05
-0.15
1.0
TA = +85°C
0.10
-0.20
0.5
SN0_ = SNC_ = AVDD/2
0.15
-0.05
TA = +25°C
-0.10
0.20
-0.15
INPUT CURRENT (nA)
TA = +25°C
VFB (V)
-0.05
18
0.1
VSW_ (V)
SCM_ = AVDD/2
0
TA = +55°C
VAIN_ (V)
0.20
0.15
-0.3
3.0
INPUT CURRENT (nA)
0
0.2
-0.2
MAX1358B toc39
-0.5
TA = +55°C
MAX1358B toc42
1.0
0.2
TA = +85°C
0.3
MAX1358B toc40
2.0
TA = +85°C
INPUT CURRENT (nA)
TA = +85°C
2.5
OUT_ = AVDD/2
0.3
INPUT CURRENT (nA)
3.0
0.4
MAX1358B toc36
3.5
INPUT CURRENT (nA)
0.4
MAX1358B toc35
4.0
FB LEAKAGE CURRENT
vs. INPUT VOLTAGE
MAX1358B toc37
AIN_ LEAKAGE CURRENT
vs. INPUT VOLTAGE
INPUT CURRENT (nA)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
0 100 200 300 400 500 600 700 800 900 1000 1100
OUTPUT CODE
______________________________________________________________________________________
2.5
3.0
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
DAC DNL vs. OUTPUT CODE
0.1
0
OUTPUT CODE
DAC OUTPUT VOLTAGE
vs. ANALOG SUPPLY VOLTAGE
DAC OUTPUT VOLTAGE
vs. TEMPERATURE
DAC FB_ INPUT BIAS CURRENT
vs. TEMPERATURE
0.62400
0.62395
VREF = 1.25V
CODE = 0x200
RLOAD = 10kI
0.62390
0.62385
2.1
2.4
2.7
3.0
0.6242
0.6238
0.6230
AVDD (V)
DAC GAIN ERROR vs.TEMPERATURE
-15
10
MAX1358B toc49
VREF = 1.25V EXTERNAL
AVDD = DVDD = 1.8V
MAX1358B toc48
150
100
FB_ = AVDD
50
FB_ = 0
35
60
85
-50
-40
-15
10
35
60
85
TEMPERATURE (°C)
DAC OUTPUT NOISE (0.1Hz TO 10Hz)
0.3
GAIN ERROR (LSB)
-40
200
0
TEMPERATURE (°C)
0.5
0.4
VREF = 1.25V EXTERNAL
CODE = 0x200
RLOAD = 10kI
AVDD = DVDD = 1.8V
0.6234
3.6
3.3
0.6246
INPUT CURRENT (pA)
0.62405
250
MAX1358B toc47
DAC OUTPUT VOLTAGE (V)
MAX1358B toc46
0.6250
1100
900
1000
800
700
600
0
1100
900
1000
800
700
600
500
400
300
OUTPUT CODE
0.62410
1.8
200
0
OUTPUT CODE
0.62415
0.62380
100
1100
900
1000
800
-0.5
700
-0.5
600
-0.4
-0.5
500
-0.4
400
-0.3
-0.4
300
-0.2
-0.3
200
-0.2
-0.3
0
-0.2
500
-0.1
400
-0.1
300
-0.1
0
200
0
INL (LSB)
0.1
INL (LSB)
0.2
0.1
MAX1358B toc45
0.3
0.2
0.62420
DAC OUTPUT VOLTAGE (V)
0.3
VREF = 2.048V
0.4
0.2
100
INL (LSB)
0.3
AVDD = 1.8V
VREF = 1.25V
0.4
0.5
100
MAX1358B toc43
VREF = 2.048V
0.4
DAC DNL vs. OUTPUT CODE
0.5
MAX1358B toc44
DAC INL vs. OUTPUT CODE
0.5
MAX1358B toc50
REF = 1.25V
AVDD = DVDD = 1.8V
CODE = 0x3FF
0.2
20µV/div
AC-COUPLED
0.1
0
VREF = 2.5V EXTERNAL
AVDD = DVDD = 3.0V
-0.1
-0.2
-0.3
OFFSET MEASURED AT CODE 0x52
-40
-15
10
35
60
85
1s/div
TEMPERATURE (°C)
______________________________________________________________________________________
19
MAX1358B
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
DAC OUTPUT-NOISE DENSITY
vs. FREQUENCY
NOISE (nV/√Hz)
VREF = 1.25V
AVDD = DVDD = 1.8V
CODE = 3FF
DAC LARGE-SIGNAL STEP RESPONSE
(0x052 TO 0x3FF)
MAX1358B toc52
MAX1358B toc51
1000
OUT_ = FB_
SCLK
2V/div
100
10
OUTA
500mV/div
0V
1
0.01
0.10
1.00
10.00
100.00
10µs/div
FREQUENCY (kHz)
DAC LARGE-SIGNAL STEP RESPONSE
(0x3FF to 0x052)
OP-AMP INPUT OFFSET VOLTAGE
vs. TEMPERATURE
-0.1
25
-0.2
-0.3
-0.5
10µs/div
15
10
-0.4
0V
20
5
-40
-15
10
35
60
85
0
TEMPERATURE (°C)
OFFSET (mV)
OP-AMP OUTPUT VOLTAGE
vs. LOAD CURRENT
0.89966
UNITY GAIN
VIN = 0.9V
AVDD = DVDD = 1.8V
0.89964
0.89960
UNITY GAIN
VIN = 1.5V
AVDD = DVDD = 3.0V
1.49955
0.89958
1.49950
0.89956
0.89954
1.49945
0.89952
-2.0 -1.5 -1.0 -0.5
0
0.5
LOAD CURRENT (mA)
20
1.49965
1.49960
0.89962
0.89950
1.49970
OP-AMP OUTPUT VOLTAGE (V)
0.89968
MAX1358B toc56
0.89970
OP-AMP OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1358B toc57
OUTA
500mV/div
30
OCCURRENCES
OFFSET VOLTAGE (mV)
SCLK
MAX1358B toc55
VCM = 0.5V
OUT_ = FB_
OP-AMP INPUT OFFSET HISTOGRAM
35
MAX1358B toc54
0
-2.92
-2.62
-2.32
-2.02
-1.72
-1.42
-1.12
-0.82
-0.52
-0.22
0.08
0.38
0.68
0.98
1.28
MAX1358B toc53
OP-AMP OUTPUT VOLTAGE (V)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
1.0
1.5
2.0
1.49940
-2.0 -1.5 -1.0 -0.5
0
0.5
1.0
1.5
LOAD CURRENT (mA)
______________________________________________________________________________________
2.0
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
OP-AMP OUTPUT VOLTAGE
vs. TEMPERATURE
OP-AMP OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
0.8984
0.8983
0.8982
MAX1358B toc59
0.49985
20µV/div
AC-COUPLED
0.49980
0.49975
0.49970
0.49965
10
35
0.49960
85
60
SUPPLY VOLTAGE (V)
OP-AMP OUTPUT-NOISE DENSITY
vs. FREQUENCY
OP-AMP UNITY-GAIN INPUT RANGE
CLOSED-LOOP OP-AMP GAIN AND PHASE
vs. FREQUENCY
10
MAX1358B toc61
VIN+ = 0.5V
AVDD = DVDD = 1.8V
UNITY GAIN
AVDD = DVDD = 3.6V
UNITY GAIN
NO LOAD
8
6
0
-2
0.10
1.00
10.00
20
45
0
0
-8
-60
-10
-80
100.00
FREQUENCY (kHz)
0
0.6
1.2
1.8
2.4
3.6
3.0
-45
PHASE
-90
CLOSED-LOOP GAIN = 1000
RLOAD = 10kI
CLOAD = 200pF
10
100
1k
-135
-180
10k
100k
1M
FREQUENCY (Hz)
VIN (V)
SPDT ON-RESISTANCE
vs. SCM_ VOLTAGE
SPST ON-RESISTANCE vs. SW_ VOLTAGE
70
MAX1358B toc64
45
ISCM_ = 1mA
40
ISW_ = 1mA
65
60
35
RON (I)
RON (I)
0.01
90
-40
-6
1
GAIN
-20
-4
180
135
60
40
2
10
MAX1358B toc63
80
4
VOUT - VIN (mV)
100
1s/div
1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
TEMPERATURE (°C)
30
AVDD = 3V
AVDD = 3V
50
45
25
20
55
AVDD = 1.8V
40
AVDD = 1.8V
0
0.5
35
1.0
1.5
VSCM_ (V)
2.0
2.5
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
VSW_ (V)
______________________________________________________________________________________
21
PHASE (°)
-15
MAX1358B toc65
-40
1000
NOISE (nV/√Hz)
0.49990
UNITY GAIN
VIN1+ = 0.5V
AVDD = DVDD = 1.8V
MAX1358B toc62
0.8981
MAX1358B toc60
GAIN (dB)
OUTPUT VOLTAGE (V)
0.8985
OP-AMP OUTPUT NOISE (0.1Hz TO 10Hz)
UNITY GAIN
VIN = 0.5V
RLOAD = 10kI
0.49995
OP-AMP OUTPUT VOLTAGE (V)
UNITY GAIN
AVDD = DVDD = 1.8V
VIN+ = AVDD/2
RLOAD = 10kI
0.8986
0.50000
MAX1358B toc58
0.8987
MAX1358B
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
SPDT ON-RESISTANCE
vs. TEMPERATURE
VSCM_ = AVDD
ISCM_ = 1mA
60
RON (I)
AVDD = DVDD = 3.0V
30
50
AVDD = DVDD = 3.0V
40
20
AVDD = DVDD = 1.8V
30
-15
10
35
60
85
AVDD = DVDD = 1.8V
-40
-15
10
35
60
85
-15
10
35
60
TEMPERATURE (°C)
SPDT SWITCHING TIME
vs. SUPPLY VOLTAGE
SPST SWITCHING TIME
vs. SUPPLY VOLTAGE
SPDT/SPST SWITCHING TIME
vs. TEMPERATURE
60
TIME (ns)
50
tON
40
tON
50
40
30
2.4
2.7
3.0
3.3
20
3.6
1.8
2.1
2.4
2.7
3.0
3.3
3.6
tON
30
20
tOFF
-40
-15
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
10
35
TEMPERATURE (°C)
60
85
10
35
60
TEMPERATURE (°C)
INTERNAL TEMPERATURE SENSOR ERROR
vs. REFERENCE VOLTAGE
15
TEMPERATURE SENSOR ERROR (°C)
VREF = 1.250V
MAX1358B toc72
2.0
-15
0
AVDD, DVDD (V)
INTERNAL TEMPERATURE SENSOR ERROR
vs. AMBIENT TEMPERATURE
TEMPERATURE SENSOR ERROR (°C)
40
10
AVDD, DVDD (V)
-40
RLOAD = 1kI
CLOAD = 35pF
tOFF
tOFF
2.1
50
85
MAX1358B toc71
MAX1358B toc69
70
30
22
-40
TEMPERATURE (°C)
60
1.8
0.001
TEMPERATURE (°C)
70
20
0.010
SWITCHING TIME (ns)
-40
0.100
MAX1358B toc70
10
VIN = AVDD
MAX1358B toc73
RON (I)
40
1.000
LEAKAGE CURRENT (nA)
VSCM_ = AVDD
ISCM_ = 1mA
MAX1358B toc67
70
MAX1358B toc66
50
SPST LEAKAGE CURRENT
vs. TEMPERATURE
MAX1358B toc68
SPDT ON-RESISTANCE
vs. TEMPERATURE
TIME (ns)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
TA = +85°C
10
TA = +27°C
5
0
TA = -40°C
-5
-10
-15
1.21
1.23
1.25
1.27
REFERENCE VOLTAGE (V)
______________________________________________________________________________________
1.29
85
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
CHARGE-PUMP OUTPUT VOLTAGE
vs. OUTPUT CURRENT
2.1
1.8
3.4
3.2
3.1
-15
10
35
3.0
85
60
MAX1358B toc77
AVDD = DVDD = 1.8V
IOUT = 10mA
60
40
20
0
0
5
10
0
2
4
6
3.10
10
8
-40
-15
15
CAPACITANCE (µF)
20
10
35
60
85
TEMPERATURE (°C)
CHARGE-PUMP OUTPUT-VOLTAGE
RIPPLE vs. OUTPUT CURRENT
CHARGE-PUMP OUTPUT RESISTANCE
vs. CAPACITANCE
80
3.18
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
100
3.22
3.14
25
CHARGE-PUMP OUTPUT-VOLTAGE RIPPLE (mVP-P)
-40
AVDD = DVDD = 1.8V
ILOAD = 10mA
3.26
3.3
DVDD SUPERVISOR
1.5
3.30
MAX1358B toc76
AVDD = DVDD = 1.8V
OUTPUT VOLTAGE (V)
CPOUT SUPERVISOR
2.4
3.5
MAX1358B toc75
2.7
OUTPUT RESISTANCE (I)
VOLTAGE THRESHOLD (V)
FALLING
CHARGE-PUMP OUTPUT VOLTAGE (V)
MAX1358B toc74
3.0
CHARGE-PUMP OUTPUT VOLTAGE
vs. TEMPERATURE
50
MAX1358B toc78
VOLTAGE SUPERVISOR THRESHOLD
vs. TEMPERATURE
AVDD = DVDD = 1.8V
40
30
20
10
0
0
2
4
6
8
10
OUTPUT CURRENT (mA)
______________________________________________________________________________________
23
MAX1358B
Typical Operating Characteristics (continued)
(DVDD = AVDD = 1.8V, VREF = +1.25V, CCPOUT = 10µF, TA = +25°C, unless otherwise noted.)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Pin Description
PIN
24
NAME
FUNCTION
1
CLK
2
UPIO2
User-Programmable Input/Output 2. See the UPIO2_CTRL Register section for functionality.
Clock Output. Default is 2.457MHz output clock for the μC.
3
UPIO3
User-Programmable Input/Output 3. See the UPIO3_CTRL Register section for functionality.
4
UPIO4
User-Programmable Input/Output 4. See the UPIO4_CTRL Register section for functionality.
5
DOUT
Serial-Data Output. Data is clocked out on SCLK’s falling edge. High impedance when CS is high, when
UPIO/SPI pass-through mode is enabled, DOUT mirrors the state of UPIO1.
6
SCLK
7
DIN
Serial-Data Input. Data is clocked in on SCLK’s rising edge.
8
CS
Active-Low Chip-Select Input. Data is not clocked into DIN unless CS is low. When CS is high, DOUT is high
impedance. High impedance when CS is high; when UPIO/SPI pass-through mode is enabled, DOUT
mirrors the state of UPIO1.
9
INT
Programmable Active-High/Low Interrupt Output. ADC, UPIO wake-up, alarm, and voltage-monitor events.
10
CLK32K
32kHz Clock Input/Output. Outputs 32kHz clock for the μC. Can be programmed as an input by enabling
the IO32E bit to accept an external 32kHz input clock. The RTC, PWM, and watchdog timer always use the
internal 32kHz clock derived from the 32kHz crystal.
11
RESET
12
32KOUT
13
32KIN
32kHz Crystal Input. Connect an external 32kHz watch crystal between 32KIN and 32KOUT.
14
SNO1
Analog Switch 1 Normally Open Terminal. Analog input to mux.
15
SCM1
Analog Switch 1 Common Terminal. Analog input to mux.
16
SNC1
Analog Switch 1 Normally Closed Terminal. Analog input to mux (open on POR).
17
SNO2
Analog Switch 2 Normally Open Terminal. Analog input to mux.
18
SCM2
Analog Switch 2 Common Terminal. Analog input to mux (open on POR).
19
SNC2
Analog Switch 2 Normally Closed Terminal. Analog input to mux.
20
OUT1
21
IN1-
Amplifier 1 Inverting Input. Analog input to mux.
22
IN1+
Amplifier 1 Noninverting Input
Serial-Clock Input. Clocks data in and out of the serial interface.
Active-Low, Open-Drain Reset Output. Remains low while DVDD is below the 1.8V voltage threshold and
stays low for a timeout period (tDSLP) after DVDD rises above the 1.8V threshold. RESET also pulses low
when the watchdog timer times out and holds low during POR until the 32kHz oscillator stabilizes.
32kHz Crystal Output. Connect an external 32kHz watch crystal between 32KIN and 32KOUT.
Amplifier 1 Output. Analog input to mux.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
PIN
NAME
FUNCTION
23
SWA
DACA SPST Shunt Switch Input. Connects to OUTA through an SPST switch.
24
FBA
DACA Force-Sense Feedback Input. Analog input to mux.
25
OUTA
26
AGND
Analog Ground
27
AVDD
Analog Supply Voltage. Also ADC reference voltage during AVDD measurement. Bypass to AGND with
10μF and 0.1μF capacitors in parallel as close to the pin as possible.
28
SWB
DACB SPST Shunt Switch Input. Connects to OUTB through an SPST switch.
29
FBB
DACB Force-Sense Feedback Input. Analog input to mux.
30
OUTB
Force-Sense DACB Ouput. Analog input to mux.
31
AIN2
Analog Input 2. Analog input to mux. Inputs have internal programmable current source for external
temperature measurement.
32
AIN1
Analog Input 1. Analog input to mux. Inputs have internal programmable current source for external
temperature measurement.
33
REF
Reference Input/Output. Output of the reference buffer amplifier or external reference input. Disabled at
power-up to allow external reference. Reference voltage for ADC and DACs.
34
REG
Linear Voltage-Regulator Output. Charge-pump-doubler input voltage. Bypass REG with a 10μF capacitor
to DGND for charge-pump regulation.
DACA Force-Sense Output. Analog input to mux.
35
CF-
36
CF+
37
CPOUT
38
DVDD
39
DGND
Digital Ground. Also ground for cascaded linear voltage regulator and charge-pump doubler.
40
UPIO1
User-Programmable Input/Output 1. See the UPIO1_CTRL Register for functionality.
—
EP
Charge-Pump Flying Capacitor Terminals. Connect an external 10μF (typ) capacitor between CF+ and CF-.
Charge-Pump Output. Connect an external 10μF (typ) reservoir capacitor between CPOUT and DGND. There is
a low threshold diode between DVDD and CPOUT. When the charge pump is disabled, CPOUT is pulled up
within 300mV (typ) of DVDD.
Digital Supply Voltage. Bypass to DGND with 10μF and 0.1μF capacitors in parallel as close to the pin as
possible.
Exposed Pad. Leave unconnected or connect to AGND.
______________________________________________________________________________________
25
MAX1358B
Pin Description (continued)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Detailed Description
The MAX1358B DAS features a multiplexed differential
16-bit ADC, 10-bit force-sense DACs, an RTC with an
alarm, a selectable bandgap voltage reference, a signaldetect comparator, 1.8V and 2.7V voltage monitors, and
wake-up control circuitry, all controlled by a 4-wire serial
interface (see Figure 3 for the functional diagram).
CS
SCLK
DIN
32.768kHz
OSCILLATOR
The 16-bit ADC features programmable continuous conversion rates as shown in Table 4, and gains of 1, 2, 4,
and 8 (Table 5) to suit applications with different power
CLK
INT
4.9152MHz HF
OSCILLATOR
AND FLL
INTERRUPT
CLK32K
32KOUT
32KIN
DVDD
The DAS directly interfaces to various sensor outputs
and, once configured, provides the stimulus, signal conditioning, and data conversion, as well as µP support.
See the Applications section for sample MAX1358B
applications.
CLK32K
M32K
INPUT/OUTPUT
CONTROL
SERIAL
INTERFACE
DOUT
32K
UPIO2
CRDY UPR
UPF
STATUS
ALD
SDC
ADD
ADOU
LDVD
LCPD
PWM
RTC AND
ALARM
WATCHDOG
TIMER
AIN1
SNO1
FBA
SCM1
FBB
SNC1
IN1TEMP+
REF
AGND
AIN2
SNO1
SNC1
SCM1
SPDT1
SNC2
SPDT2
TEMPSNO2
OUTA
SCM2
OUTB
SNC2
OUT1
AIN2
REF
AGND
DGND
UPIO4
DVDD (1.8V)
VOLTAGE
MONITOR
CHARGEPUMP
DOUBLER
LINEAR 1.65V
VOLTAGE
REGULATOR
M32K
CF+
CFREG
PROG. VOS
PGA
1.25V BANDGAP
10:1
MUX
POS
REF
CMP
AV = 1, 1.6384, 2 V/V
REF
REF
IN+
16-BIT ADC
IN-
POLARITY
FLIPPER
10-BIT DAC
OUTA
BUF
HFCLK
SWA
AV = 1, 2, 4, 8 V/V
FBA
REF
10:1
MUX
NEG
10-BIT DAC
OUTB
BUF
SWB
OP1
FBB
IN1+
IN1-
OUT1
AGND
Figure 3. Functional Diagram
26
RESET
CPOUT
DVDD M32K
MAX1358B
PGA
SNO2
SCM2
TEMP+
TEMP-
UPIO3
4
4
CPOUT (2.7V)
VOLTAGE
MONITOR
AIN2
TEMP
SENSOR
AIN1
UPIO
WDTO
AIN1
PROG
CURRENT
SOURCE
UPIO1
16
HFCLK
CONTROL
LOGIC
AVDD
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ADC Modulator
The MAX1358B performs analog-to-digital conversions
using a single-bit, 3rd-order, switched-capacitor sigmadelta modulator. The sigma-delta modulation converts
the input signal into a digital pulse train whose average
duty cycle represents the digitized signal information.
The pulse train is then processed by a digital decimation
filter. The modulator provides 2nd-order frequency shaping of the quantization noise resulting from the single-bit
quantizer. The modulator is fully differential for maximum
signal-to-noise ratio and minimum susceptibility to
power-supply noise.
Analog-to-Digital Converter (ADC)
INT asserts (and remains asserted) within 30µs when
the differential voltage on the selected analog inputs
exceeds the signal-detect comparator trip threshold.
The signal-detect comparator’s differential input trip
threshold (i.e., offset) is user selectable and can be programmed to the following values: 0mV, 50mV, 100mV,
150mV, or 200mV.
The MAX1358B includes a sigma-delta ADC with programmable conversion rate, a PGA, and a dual 10:1
input mux. When performing continuous conversions at
10sps or single conversions at the 40sps setting (effectively 10sps due to four sample sigma-delta settling),
the ADC has 16-bit noise-free resolution. The noise-free
resolution drops to 10 bits at the maximum sampling
rate of 477sps. Differential inputs support unipolar
(between 0 and VREF) and bipolar (between ±VREF)
modes of operation. Note: Avoid combinations of input
signal and PGA gains that exceed the reference range
at the ADC input. The ADOU bit in the STATUS register
indicates if the ADC has overranged or underranged.
Zero-scale and full-scale calibrations remove offset and
gain errors. Direct access to gain and zero-scale calibration registers allows system-level offset and gain calibration. The zero-scale adjustment register allows
intentional positive offset skewing to preserve unipolarmode resolution for signals that have a slight negative
offset (i.e., unipolar clipping near zero can be removed).
Perform ADC calibration whenever the ADC configuration, temperature, or AVDD changes. The ADC-done status can be programmed to provide an interrupt on INT
or on any UPIO_.
PGA Gain
An integrated PGA provides four selectable gains (+1V/V,
+2V/V, +4V/V, and +8V/V) to maximize the dynamic
range of the ADC. Bits GAIN1 and GAIN0 set the gain
(see the ADC Register for more information). The PGA
gain is implemented in the digital filter of the ADC.
Signal-Detect Comparator
Analog Inputs
The ADC provides two external analog inputs: AIN1
and AIN2. The rail-to-rail inputs accept differential or
single-ended voltages, or external temperature-sensing
diodes. The unused op amps, switches, or DAC inputs
and output pins can also be used as rail-to-rail analog
inputs if the associated function is disabled.
Analog Input Protection
Internal protection diodes clamp the analog inputs to
AVDD and AGND and allow the channel input to swing
from (AGND - 0.3V) to (AVDD + 0.3V). For accurate
conversions near full scale, the inputs must not exceed
AVDD by more than 50mV or be lower than AGND by
50mV. If the inputs exceed (AGND - 0.3V) to (AVDD +
0.3V), limit the current to 50mA.
Analog Mux
The MAX1358B includes a dual 10:1 mux for the positive
and negative inputs of the ADC. Figure 3 illustrates which
signals are present at the inputs of each mux for the
MAX1358B. The MUXP[3:0] and MUXN[3:0] bits of the
MUX register select the input to the ADC and the signaldetect comparator (Tables 8 and 9). See the MUX register
description in the Register Definitions section for multiplexer functionality. The POL bit of the ADC register
swaps the polarity of mux output signals to the ADC.
______________________________________________________________________________________
27
MAX1358B
and dynamic range constraints. The force-sense DAC
provides 10-bit resolution for precise sensor applications. The ADC and DACs both utilize a low-drift 1.25V
internal bandgap reference for conversions and fullscale range setting. The RTC has a 138-year range and
provides an alarm function that can be used to wake up
the system or cause an interrupt at a predefined time.
The power-supply voltage monitor detects when DVDD
falls below a trip threshold voltage of +1.8V and asserts
RESET. The MAX1358B uses a 4-wire serial interface to
communicate directly among SPI, QSPI, or
MICROWIRE devices for system configuration and
readback functions.
Digital Filtering
Force-Sense DAC
The MAX1358B contains an on-chip digital lowpass filter that processes the data stream from the modulator
using a sinc4 (sinx/x)4 response. The sinc4 filter has a
settling time of four output data periods (4 x 200ms).
The MAX1358B incorporates two 10-bit force-sensing
DACs. The DACs’ reference voltage sets the full-scale
range. Program the DACA_OP register using the serial
interface to set the output voltages of the DAC at OUTA.
Connecting resistors in a voltage-divider configuration
between OUTA, FBA, and GND sets a different closedloop gain for the output amplifier (see the Applications
Information section).
The DAC output amplifier typically settles to ±0.5 LSB
from a full-scale transition within 65µs (unity gain and
loaded with 10kΩ in parallel with 200pF). Loads of less
than 1kΩ could degrade performance. See the Typical
Operating Characteristics for the source-and-sink
capability of the DAC output.
The MAX1358B features a software-programmable
shutdown mode for the DAC. Power down DACA or
DACB independently or simultaneously by clearing the
DAE and DBE bits (see the DACA_OP Register and
DACB_OP Register sections). DAC output OUTA and
OUTB go high impedance when powered down. The
DACs are normally powered down at power-on reset.
The MAX1358B has 25% overrange capability built into
the modulator and digital filter:
4
⎡
⎛
f ⎞⎤
⎢ SIN⎜ Nπ ⎟ ⎥
fm ⎠ ⎥
⎝
1
H(f) = ⎢⎢
N
⎛
⎞ ⎥
⎢ SIN⎜ π f ⎟ ⎥
⎢⎣
⎝ fm ⎠ ⎥⎦
Figure 4 shows the filter frequency response. The sinc4
characteristic -3dB cutoff frequency is 0.228 times the
first notch frequency.
The output data rate for the digital filter corresponds
with the positioning of the first notch of the filter’s frequency response. The notches of the sinc4 filter are
repeated at multiples of the first notch frequency. The
sinc4 filter provides an attenuation of better than 100dB
at these notches. For example, 50Hz is equal to five
times the first notch frequency and 60Hz is equal to six
times the first notch frequency.
0
-40
GAIN (dB)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
-80
-120
Charge Pump
The charge pump provides > 3V at CPOUT with a maximum 10mA load. Enable the charge pump through the
PS_VMONS register. The charge pump is powered
from DVDD. See Figures 5 and 6 for block diagrams of
the charge pump and linear regulator. The charge
pump is disabled at power-on reset.
An internal clock drives the charge-pump clock and
ADC clock. The charge pump delivers a maximum
10mA of current to external devices. The droop and the
ripple depend on the clock frequency (f CLK =
32.768kHz/2), switch resistances (RSWITCH = 5Ω), and
the external capacitors (10µF) along with their respective ESRs, as shown below.
VDROOP = IOUTROUT
-160
1
+ 2RSWITCH + 4ESRCF + ESRCCPOUT
fCLKCF
IOUT
VRIPPLE =
+ 2IOUTESRCCPOUT
fCLKCCPOUT
ROUT =
-200
0
20
40
60
80
FREQUENCY (Hz)
100
120
Figure 4. Filter Frequency Response
28
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
DVDD
LDOE
CPE
CPOUT
1.22V
OP
M32K
1.65V
NONOVERLAP
CLOCK GENERATOR
REG
CF+
REG
CF-
LDOE
CHARGE-PUMP DOUBLER
LINEAR 1.65V VOLTAGE REGULATOR
Figure 5. Linear-Regulator Block Diagram
Voltage Supervisors
The MAX1358B provides voltage supervisors to monitor
DVDD and CPOUT. The first supervisor monitors the
DVDD supply voltage. RESET asserts and sets the corresponding LDVD status bit when DVDD falls below the
1.8V threshold voltage. When the DVDD supply voltage
rises above the threshold during power-up, RESET
deasserts after a nominal 1.5s timeout period to give the
crystal oscillator time to stabilize. Set the threshold hysteresis using the HYSE bit of the PS_VMONS register.
See the PS_VMONS Register section for configuring hysteresis. There is no separate voltage monitor for AVDD,
but the analog supply is covered by the DVDD monitor in
many applications where DVDD and AVDD are externally
connected together. Multiple supply applications where
AVDD and DVDD are not connected together require a
separate external voltage monitor for AVDD. See Figure 7
for a block diagram of the DVDD voltage supervisor.
The second voltage monitor tracks the charge-pump
output voltage, CPOUT. If CPOUT falls below the 2.7V
threshold, a corresponding register status bit (LCPD) is
Figure 6. Charge-Pump Block Diagram
set to flag the condition. The CPOUT monitor output
can also be mapped to the interrupt generator and output on INT. The CPOUT monitor can be used as a 3V
AVDD monitor in applications where the charge pump is
disabled and CPOUT is connected to AV DD . AV DD
must be greater or equal to DVDD when CPOUT is used
to monitor AVDD. See Figure 8 for a block diagram of the
CPOUT voltage supervisor.
Interrupt Generator (INT)
The interrupt generator provides an interrupt to an
external µC. The source of the interrupt is generated by
the status register and can be masked and unmasked
through the IMSK register. CRDY is unmasked by
default, and INT is active-high at power-on reset. INT is
programmable as active-high and active-low. Possible
sources include a rising or falling edge of UPIO_, an
RTC alarm, an ADC conversion completion, or the voltage-supervisor outputs. The interrupt causes INT to
assert when configured as an interrupt output.
______________________________________________________________________________________
29
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
WDTO
DVDD
HYSE POR
LSDE
1.8VTH
ANALOG
2:1 MUX
CMP
2.0VTH
RSTE
RESET
CONTROL
LOGIC
1.25V
LDVD
LSDE
DVDD (1.8V) VOLTAGE MONITOR
Figure 7. DVDD Voltage-Supervisor Block Diagram
as the C-002RX32-E from Epson Crystal. Using a crystal with a CL that is larger than the load capacitance of
the oscillator circuit causes the oscillator to run faster
than the specified nominal frequency of the crystal or to
not start up. See Figures 9 and 10 for block diagrams
of the crystal oscillator and the CLK32K I/O.
CPOUT
CPDE
2.7VTH
CMP
LCPD
Real-Time Clock (RTC)
1.25V
CPDE
CPOUT (2.7V) VOLTAGE MONITOR
Figure 8. CPOUT Voltage-Supervisor Block Diagram
Crystal Oscillator
The on-chip oscillator requires an external crystal (or
resonator) connected between 32KIN and 32KOUT
with a 32.768kHz operating frequency. This oscillator is
used for the RTC, alarm, PWM, watchdog, charge
pump, and FLL. In any crystal-based oscillator circuit,
the oscillator frequency is sensitive to the capacitive
load (CL). CL is the capacitance that the crystal needs
from the oscillator circuit and not the capacitance of the
crystal. The input capacitance across 32KIN and
32KOUT is 6pF. Choose a crystal with a 32.768kHz
oscillation frequency and a 6pF capacitive load such
30
The integrated RTC provides the current time information
from a 32-bit counter and subsecond counts from an
8-bit ripple counter. An internally generated reference
clock of 256Hz (derived from the 32.768kHz crystal) drives the 8-bit subsecond counter. An overflow of the 8-bit
subsecond counter inputs a 1Hz clock to increment the
32-bit second counter. The RTC 32-bit second counter is
translatable to calendar format with firmware. All 40 bits
(32-bit second counter and 8-bit subsecond counter)
must be clocked in or out for valid data. The RTC and
the 32.768kHz crystal oscillator consume less than 1µA
when the rest of the device is powered down.
Time-of-Day Alarm
Program the AL_DAY register with a 20-bit value, which
corresponds to a time 1s to 12 days later than the current time with a 1s resolution. The alarm status bit, ALD,
asserts when the 20 bits of the AL_DAY register matches the 20 LSBs of the 32-bit second counter. The ADE
bit automatically clears when the time-of-day alarm
trips. The time-of-day alarm causes the device to exit
sleep mode.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
High-Frequency Clock
An internal oscillator and an FLL are used to generate a
4.9152MHz ±1% high-frequency clock. This clock and
derivatives are used internally by the ADC, analog
switches, and PWM. This clock signal outputs to CLK.
When the FLL is enabled, the high- frequency clock is
locked to the 32.768kHz reference. If the FLL is disabled, the high-frequency clock is free-running. At
power-up, the CLK pin defaults to a 2.4576MHz clock
output, which is compatible with most µCs. See Figure
12 for a block diagram of the high-frequency clock.
User-Programmable I/Os
The MAX1358B provides four digital programmable
I/Os (UPIO1–UPIO4). Configure UPIOs as logic inputs
or outputs using the UPIO control register. Configure
the internal pullups using the UPIO setup register, if
required. At power-up, the UPIOs are internally pulled
up to DVDD. UPIO_ outputs can be referenced to DVDD
or CPOUT. See the UPIO__CTRL Register and
UPIO_SPI Register sections for more details on configuring the UPIO_ pins.
OSCE
32K
32KOUT
32kHz
OSCILLATOR
OSCE
CK32E
IO32E
32K
IO32E
0
IO32E
2:1
MUX
32KIN
CLK32K
M32K
1
32.768kHz OSCILLATOR
CLK32K I/O CONTROL
Figure 9. 32kHz Crystal-Oscillator Block Diagram
Figure 10. CLK32K I/O Block Diagram
POR PULSES HIGH DURING POWER-UP.
WDW PULSES HIGH DURING WATCHDOG REGISTER WRITE.
WDTO
32K
WDE
DIVIDEBY-8192
D
Q
CK
Q
4Hz
D
Q
CK
R
Q
R
POR
WDW
WATCHDOG TIMER
Figure 11. Watchdog Timer Block Diagram
______________________________________________________________________________________
31
MAX1358B
Watchdog
Enable the watchdog timer by writing a 1 to the WDE
bit in the CLK_CTRL register. After enabling the watchdog timer, the device asserts RESET for 250ms, if the
watchdog address register is not written every 500ms.
Due to the asynchronous nature of the watchdog timer,
the watchdog timeout period varies between 500ms
and 750ms. Write a 0 to the WDE bit to disable the
watchdog timer. See Figure 11 for a block diagram of
the watchdog timer.
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
32.768kHz
CKSEL2
CKSEL
HFCE
FLLE
M32K
FREQUENCY
COMPARE
FREQ
ERROR
FREQUENCY
INTEGRATOR
TUNE
DIGITALLY
CONTROLLED
OSCILLATOR
CLKE
0
2:1
MUX
1, 2, 4, 8
DIVIDER
CLK
1
4.9152MHz
HFCLK
CRDY
4.9152MHz HF OSCILLATOR AND FLL
Figure 12. High-Frequency Clock and FLL Block Diagram
Program each UPIO1–UPIO4 as one of the following:
• General-purpose input
PROGRAMMABLE CURRENT SOURCE
• Power-mode control
• Analog switch (SPST) and SPDT control input
• ADC data-ready output
IVAL
CURRENT
SOURCE
IMUX
1:3
DEMUX
• General-purpose output
• PWM output
• Alarm output
AIN1
AIN1
AIN2
AIN2
• SPI pass-through
Internal and External (Remote)
Temperature Sensors
An internal transistor or a remote transistor (or diode) is
used with the ADC and a programmable current source
to measure the ambient temperature. Depending on the
method, either two or four currents are passed through
the PN junction. The voltage across the PN junction is
measured at each current. For each current, the voltage
across a series resistor is also measured. Measuring the
voltage across the resistor allows the user to determine
the precise current ratios. A microcontroller can then
use the diode equation to calculate the temperature.
The four-current method eliminates errors caused by
parasitic resistance in series with the diode, which
increases the apparent voltage across the PN junction.
When measuring temperature using the internal transistor for a sensor, the two-current method is usually adequate although the four-current method can also be
used. Refer to Application Note 4296: Measuring
Temperature with the MAX1358 Data Acquisition System
for details on the measurement procedure.
32
TEMP+
TEMP-
TEMP SENSOR
Figure 13. Temperature-Sensor Measurement Block Diagram
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Two-current method:
T = q(VBE2 - VBE1)/(n k ln(VR2/VR1))
Four-current method:
T = q(VBE2 + VBE3 - VBE1 - VBE4)/(n k ln((VR2 x
VR3)/(VR1 x VR4))
where T is the temperature in degrees Kelvin, VBEX is
the base to emitter voltage at current X, VRX is the voltage across the current-sensing resistor at current X, q
is the charge on an electron, k is Boltzmann’s constant,
and n is the ideality factor for the diode. From a practical standpoint, it is easiest to combine all the constants
into one constant that also includes the voltage resolution of the ADC in unipolar mode. This requires introducing the term VREF, which is the reference voltage of
the ADC. An N prefix on a term indicates that it is the
integer value read directly from the ADC.
Two-current method:
T = 0.1771 x VREF(NVBE2 - NVBE1)/ln(NVR2/NVR1)
Four-current method:
T = 0.1771 x VREF((NVBE2 + NVBE3 - NVBE1 NVBE4)/ln(NVR2 x NVR3/NVR1/NVR4)
The natural log function (ln) is eliminated from the calculation by using an approximation. Due to the small
part-to-part variation in current ratios, this approximation is extremely accurate.
Two-current method without an ln function:
T = 0.1771 x VREF(NVBE2 – NVBE1)/(2.7081 +
2_(NVR2/NVR1 - 15)/(NVR2/NVR1 + 15)
Four-current method without an ln function:
T = 0.1771 x VREF(NVBE2 + NVBE3 - NVBE1 NVBE4)/(2.0794 + 2(NVR2 x NVR3/NVR1/NVR4 - 8)/
(NVR2 x NVR3/NVR1/NVR4 + 8)
q = electron charge = 1.60219 x 10-19 coulombs
n = diode ideality = 1.000 (typ)
k = Boltzmann's constant = 1.3807 x 10-23 Joules/Kelvin
I1 = Nominal current (4µA)
I2 = Nominal current ng (60µA)
I3 = Nominal current (64µA)
I4 = Nominal current (120µA)
To convert the measured temperature in Kelvin to
degrees Celsius, the following formula is used:
°C = K - 273.15
For the external temperature measurement, a transistor
such as the 2N3904 is recommended.
Voltage Reference and Buffer
An internal 1.25V bandgap reference has a buffer with
a selectable 1.0V/V, 1.638V/V, or 2.0V/V gain, resulting in nominally 1.25V, 2.048V, or 2.5V reference voltage at REF. The ADC and DACs use this reference
voltage. The state of the internal voltage reference
output buffer at POR is disabled so it can be driven, at
REF, with an external reference between AGND and
AVDD. The MAX1358B reference has an initial tolerance of ±1%. Program the reference buffer through
the serial interface. Bypass REF with a 4.7µF capacitor to AGND.
Uncommitted Operational
Amplifiers (Op Amps)
The MAX1358B includes one op amp. The op amp features rail-to-rail outputs, near rail-to-rail inputs, and has
an 80kHz (1nF load) input bandwidth. The DACA_OP
(DACB_OP) register controls the power state of the op
amps. When powered down, the outputs of the op
amps is high impedance.
______________________________________________________________________________________
33
MAX1358B
The temperature equations for the two-current and fourcurrent methods are as follows:
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Single-Pole/Double-Throw (SPDT) Switches
Serial Interface
The MAX1358B provides two uncommitted SPDT switches. Each switch has a typical 35Ω on-resistance. Control
the switches through the SW_CTRL register, the PWM
output, and/or a UPIO port configured to control the
switches (UPIO1–UPIO4_CTRL register).
The MAX1358B features a 4-wire serial interface consisting of a chip select (CS), serial clock (SCLK), data
in (DIN), and data out (DOUT). CS must be low to allow
data to be clocked into or out of the device. DOUT is
high impedance while CS is high. The data is clocked
in at DIN on the rising edge of SCLK. Data is clocked
out at DOUT on the falling edge of SCLK. The serial
interface is compatible with SPI modes CPOL = 0,
CPHA = 0 and CPOL = 1, CPHA = 1. A write operation
to the MAX1358B takes effect on the last rising edge of
SCLK. If CS goes high before the complete transfer, the
write is ignored. Every data transfer is initiated by the
command byte. The command byte consists of a start
bit (MSB), R/W bit, and 6 address bits. The start bit
must be 1 to perform data transfers to the device.
Zeros clocked in are ignored. For SPI pass-through
mode, see the UPIO_SPI Register section. An address
byte identifies each register. Table 4 shows the complete register address map for this family of DAS.
Figures 14, 15, and 16 provide timing diagrams for
read and write commands.
Pulse-Width Modulator (PWM)
A single 8-bit PWM is available for various system tasks
such as LCD bias control, sensor bias voltage trim,
buzzer drive, and duty-cycled sleep-mode power-control schemes. PWM input clock sources include the
4.9512MHz FLL output, the 32kHz clock, and frequency-divided versions of each. Although most µCs have
built-in PWM functions, the MAX1358B PWM is more
flexible by allowing the UPIO outputs to be driven to
DVDD or regulated CPOUT logic-high voltage levels.
For duty-cycled power-control schemes, use the
32kHz-derived input clock. The PWM output is available independent of µC power state. The FLL is typically disabled in sleep-override mode.
34
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
CS
SCLK
X
DIN
1
0
A5
A4
A3
A2
A1
A0
DN
DN -1
DN-2
DN-3
D2
D1
D0
X
X
DOUT
X = DON’T CARE.
Figure 14. Serial-Interface Register Write with 8-Bit Control Word, Followed by a Variable Length Data Write
CS
SCLK
DIN
X
1
1
A5
A4
A3
A2
A1
A0
DOUT
X
X
X
X
X
X
X
DN
DN-1
DN-2
DN-3
D2
D1
D0
X = DON’T CARE.
Figure 15. Serial-Interface Register Read with 8-Bit Control Word, Followed by a Variable Length Data Read
CS
SCLK
DIN
1
DOUT
0 A4 A3 A2 A1 A0 X D7 D6 D5 D4 D3 D2 D1 D0
1
ADC
CONV
1 A4 A3 A2 A1 A0 X
D15D14 D13D12 D11D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
CHANGES
DRDY
X = DON’T CARE.
Figure 16. Performing an ADC Conversion (DRDY Function Can Be Accessed at UPIO Pins)
______________________________________________________________________________________
35
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Register Definitions
Table 4. Register Address Map
REGISTER
NAME
START
CTL
(R/W)
ADR
(ADDRESS)
ADC
1
R/W
0
0
0
0
0
X
MUX
DATA
OFFSET CAL
GAIN CAL
RESERVED
1
1
1
1
1
R/W
R
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
1
0
0
1
0
1
0
1
S
X
X
X
X
DACA_OP
1
R/W
0
0
1
1
0
X
D, D, D OR D
(DATA)
ADCE STRT
BIP
POL CONT ADCREF GAIN
RATE
MODE
X
X
MUXP
MUXN
ADC
OFFSET
GAIN
Reserved. Do not use.
DAE
DBE
OP1E
X
X
X
DACA
X
DACB
DACA
DACB_OP
1
R/W
0
0
1
1
1
REF_SDC
1
R/W
0
1
0
0
0
AL_DAY
1
R/W
0
1
0
0
1
RESERVED
1
R/W
0
1
0
1
0
CLK_CTRL
1
R/W
0
1
0
1
1
RTC
1
R/W
0
1
1
0
0
PWM_CTRL
1
R/W
0
1
1
0
1
PWM_THTP
1
R/W
0
1
1
1
0
WATCHDOG
NORM_MD
SLEEP
SLEEP_CFG
UPIO4_CTRL
UPIO3_CTRL
UPIO2_CTRL
UPIO1_CTRL
UPIO_SPI
SW_CTRL
TEMP_CTRL
RESERVED
1
1
1
1
1
1
1
1
1
1
1
1
W
W
W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
0
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
IMSK
1
R/W
1
1
0
1
1
RESERVED
PS_VMONS
RESERVED
1
1
1
R/W
R/W
R/W
1
1
1
1
1
1
1
1
1
0
0
1
0
1
0
STATUS
1
R
1
1
1
1
1
X
DAE
DBE
OP1E
X
X
DACB
AON SDCE
TSEL
ASEC
X
ASEC
X
X
X
X
X
Reserved. Do not use.
AWE
ADE
X
RWE RTCE
OSCE
FLLE HFCE
X
CKSEL
IO32E CK32E
CLKE
INTP WDE
SEC
X
SUB
PWME
FSEL
SWAH
SWAL SWBH SWBL
X
SPD1 SPD2
X
X
X
X
X
X
PWMTH
X
PWMTP
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
SLP SOSCE SCK32E SPWME SHDN
X
X
X
X
X
UP4MD
PUP4
SV4
ALH4 LL4
X
UP3MD
PUP3
SV3
ALH3 LL3
X
UP2MD
PUP2
SV2
ALH2 LL2
X
UP1MD
PUP1
SV1
ALH1 LL1
X
UP4S UP3S UP2S UP1S
X
X
X
X
X
SWA
SWB SPDT1
SPDT2
X
X
X
IMUX
IVAL
X
X
X
X
X
Reserved. Do not use.
MLDVD MLCPD MADO MSDC MCRDY MADD MALD X
X
MUPR
MUPF
X
Reserved. Do not use.
X
LDOE
CPE LSDE CPDE HYSE
RSTE
X
X
X
Reserved. Do not use.
LDVD LCPD ADOU SDC CRDY
ADD
ALD
X
X
UPR
UPF
X
REFV
AOFF
X = Don’t care.
36
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
ADC Register (Power-On State: 0000 0000 0000 00XX)
MSB
ADCE
LSB
STRT
BIP
RATE
The ADC register configures the ADC and starts
a conversion.
ADCE: ADC power-enable bit. ADCE = 1 powers up
the ADC, and ADCE = 0 powers down the ADC.
STRT: ADC start bit. STRT = 1 resets the registers
inside the ADC filter and initiates a conversion or calibration. The conversion begins immediately after the
16th ADC control bit is clocked by the rising edge of
SCLK. The initial conversion requires four conversion
cycles for valid output data. If CONT = 0 when STRT is
asserted, the ADC stops after a single conversion and
holds the result in the DATA register. If CONT = 1 when
STRT is asserted, the ADC performs continuous conversions at the rate specified by the RATE bits until
CONT is deasserted or ADCE is deasserted, powering
down the ADC. The STRT bit is automatically deasserted
after the initial conversion is complete (four conversion
cycles; the ADC status bit ADD in the STATUS register
asserts). The current ADC configurations are not affected if the ADC register is written with STRT = 0. This
allows the ADC and mux configurations to be updated
simultaneously with the S bit in the MUX register.
BIP: Unipolar/bipolar bit. Set BIP = 0 for unipolar mode
and BIP = 1 for bipolar mode. Unipolar-mode data is
unsigned binary format and bipolar is two’s complement.
See the ADC Transfer Functions section for more details.
POL: Polarity flipper bit. POL = 1 flips the polarity of the
differential signal to the ADC and the input to the signaldetect comparator (SDC). POL = 0 sets the positive mux
output to the positive ADC and SDC inputs, and the negative mux output to the negative ADC and SDC inputs.
POL = 1 sets the positive mux output to the negative
ADC and SDC inputs, and the negative mux output to
the positive ADC and SDC inputs.
POL
CONT
ADCREF
MODE
GAIN
X
X
CONT: Continuous conversion bit. CONT = 1 enables
continuous conversions following completion of the first
conversion or calibration(s) initiated by the STRT or S
bit. Set CONT = 0 while asserting the STRT bit, or prior
to asserting the S bit to perform a single conversion or to
prevent conversions following a calibration. Set
CONT = 0 to abort continuous conversions already in
progress. When the ADC is stopped in this way, the last
complete conversion result remains in the DATA register
and the internal ADC state information is lost. Asserting
the CONT bit does not restart the ADC, but results in
continuous conversions once the ADC is restarted with
the STRT or S bit.
ADCREF: ADC reference source bit. Set ADCREF = 0
to select REF as the ADC reference. Set ADCREF = 1
to select AVDD as the ADC reference. To measure the
AVDD voltage without having to attenuate the supply
voltage, select REF and AGND as the differential inputs
to the ADC, with POL = 0 and while ADCREF = 1.
GAIN: ADC gain-setting bits. These two bits
select the gain of the ADC as shown in Table 5.
Table 5. Setting the Gain of the ADC
GAIN SETTING (V/V)
GAIN1
GAIN0
1
0
0
2
0
1
4
1
0
8
1
1
______________________________________________________________________________________
37
MAX1358B
Register Bit Descriptions
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Table 6a. Setting the ADC Conversion Rate*
CONTINUOUS
CONVERSION
RATE (sps)
SINGLE
CONVERSION
RATE (sps)
RATE2
RATE1
RATE0
10
2.5
0
0
0
40
10
0
0
1
50
12.5
0
1
0
60
15
0
1
1
200
50
1
0
0
240
60
1
0
1
400
100
1
1
0
477
128
1
1
1
Table 6b. Actual ADC Conversion Rates
NOMINAL
CONTINUOUS
CONVERSION
RATE (sps)
DECIMATION
RATIO
ACTUAL
CONTINUOUS
CONVERSION
RATE (sps)
10
1096
10.01
40
274
40.04
50
220
49.87
60
183
59.95
200
55
199.48
240
46
238.51
400
27
406.35
477
23
477.02
*Calculate the ADC sampling rate using the following
equation:
fHFCLK
fS =
448 × decimation ratio
where fHFCLK = 4.9152MHz nominally.
38
RATE: ADC conversion-rate-setting bits. These
three bits set the conversion rate of the ADC as shown
in Table 6. The initial conversion requires four conversion cycles for valid data, and subsequent conversions
require only one cycle (if CONT = 1). A full-scale input
change can require up to five cycles for valid data if
the digital filter is not reset with the STRT or S bit.
MODE: Conversion-mode bits. These three bits
determine the type of conversion for the ADC as shown
in Table 7. When the ADC finishes an offset calibration
and/or gain calibration, the MODE bits clear to 0
hex, the ADD bit in the STATUS register asserts, and
an interrupt asserts on INT (or UPIO_ if programmed as
DRDY) if MADD is unmasked. Perform a gain calibration after achieving the desired offset (calibrated or
not). If an offset and gain calibration are performed
together (MODE = 7 hex), the offset calibration is
performed first followed by the gain calibration, and the
µC is interrupted by INT (or UPIO_ if programmed as
DRDY) if MADD is unmasked only upon completion of
both offset and gain calibration. After power-on or calibration, the ADC does not begin conversions until initiated by the user (see the ADCE and STRT bit
descriptions in this section and see the S bit descriptions in the MUX Register section). See the GAIN CAL
Register and OFFSET CAL Register sections for details
on system calibration.
Table 7. Setting the ADC Conversion Mode
CONVERSION MODE
MODE2
MODE1
MODE0
Normal
0
0
0
System Offset Calibration
0
0
1
System Gain Calibration
0
1
0
Normal
0
1
1
Normal
1
0
0
Self-Offset Calibration
1
0
1
Self-Gain Calibration
1
1
0
Self-Offset and Gain
Calibration
1
1
1
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
S (ADR0)
MUXP3
LSB
MUXP2
MUXP1
MUXP0
The MUX register configures the positive and negative
mux inputs and can start an ADC conversion.
S (ADR0): Conversion start bit. The S bit is the LSB of
the MUX register address byte. S = 1 resets the registers inside the ADC filter and initiates a conversion or
calibration. The conversion begins immediately after
the eighth MUX register data bit, when S = 1 and when
writing to the MUX register. This allows the new MUX
and ADC register settings to take effect simultaneously
for a new conversion, if STRT = 0 during the last write
to the ADC register. If the S bit is asserted and the
command is a read from the MUX register, the conversion starts immediately after the S bit (ADR0) is clocked
in by the rising edge of SCLK.
Read the MUX register with S = 1 for the fastest method
of initiating a conversion because only 8 bits are
required. The subsequent MUX register read is valid,
but can be aborted by raising CS with no harmful side
effects. The initial conversion requires four conversion
cycles for valid output data. If CONT = 0 and S = 1, the
ADC stops after a single conversion and holds the
result in the DATA register. If CONT = 1 and S = 1, the
ADC performs continuous conversions at the rate
Table 8. Selecting the Positive MUX Inputs
MUXN3
MUXN2
MUXN1
MUXN0
specified by the RATE bits until CONT deasserts
or ADCE deasserts, powering down the ADC. When a
conversion initiates using the S bit, the STRT bit asserts
and deasserts automatically after the initial conversion
completes. Writing to the MUX register with S = 0 causes the MUX settings to change immediately and the
ADC continues in its prior state with its settings unaffected. When the ADC is powered down, MUX inputs
are open.
MUXP: MUX positive input bits. These four bits
select one of 10 inputs from the positive MUX to go to the
positive output of the MUX as shown in Table 8. Any
writes to the MUX register take effect immediately once
the LSB (MUXN0) is clocked by the rising edge of SCLK.
MUXN MUX negative input bits. These four bits
select one of 10 inputs from the negative MUX to go to
the negative output of the MUX as shown in Table 9. Any
writes to the MUX register take effect immediately once
the LSB (MUXN0) is clocked by the rising edge of SCLK.
The DATA register contains the data from the most
recently completed conversion.
The OFFSET CAL register contains the 24-bit data of
the most recently completed offset calibration.
Table 9. Selecting the Negative MUX Inputs
POSITIVE MUX
INPUT
MUXP3
MUXP2
MUXP1
MUXP0
NEGATIVE
MUX INPUT
MUXN3
MUXN2
MUXN1
MUXN0
AIN1
0
0
0
0
TEMP-
0
0
0
0
SNO1
0
0
0
1
SNO2
0
0
0
1
FBA
0
0
1
0
OUTA
0
0
1
0
1
SCM1
0
0
1
1
SCM2
0
0
1
FBB
0
1
0
0
OUTB
0
1
0
0
SNC1
0
1
0
1
SNC2
0
1
0
1
0
IN1-
0
1
1
0
OUT1
0
1
1
TEMP+
0
1
1
1
AIN2
0
1
1
1
REF
1
0
0
0
REF
1
0
0
0
AGND
AGND
Open
X = Don’t care.
1
0
0
1
1
0
1
X
1
1
X
X
Open
1
0
0
1
1
0
1
X
1
1
X
X
X = Don’t care.
______________________________________________________________________________________
39
MAX1358B
MUX Register (Power-On State: 0000 0000)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
DATA Register (Power-On State: 0000 0000 0000 0000)
MSB
ADC15
ADC14
ADC13
ADC12
ADC11
ADC10
ADC9
ADC8
LSB
ADC7
ADC6
ADC5
ADC4
ADC Analog-to-digital conversion data bits.
These 16 bits are the results from the most recently
completed conversion. The data format is unsigned,
ADC3
ADC2
ADC1
ADC0
binary for unipolar mode, and two’s complement for
bipolar mode.
OFFSET CAL Register (Power-On State: 0000 0000 0000 0000 0000 0000)
MSB
OFFSET23
OFFSET22
OFFSET21
OFFSET20
OFFSET19
OFFSET18
OFFSET17
OFFSET16
OFFSET15
OFFSET14
OFFSET13
OFFSET12
OFFSET11
OFFSET10
OFFSET9
OFFSET8
LSB
OFFSET7
OFFSET6
OFFSET5
OFFSET4
OFFSET: Offset-calibration bits. The data format
is two’s complement and is subtracted from the ADC
output before being written to the DATA register. The
offset calibration allows input offset errors between
VREF ±50% to be corrected in unipolar or bipolar mode.
The MAX1358B can perform system offset calibration
or self-offset calibration. Self-calibration performs a cal-
OFFSET3
OFFSET2
OFFSET1
OFFSET0
ibration for the entire signal path. See the ADC
Calibration section for more details.
The ADC input voltage range specifications must
always be obeyed, and the OFFSET CAL register effectively offsets the ADC digital scale to a “zero” value
determined by the calibration.
GAIN CAL Register (Power-On State: 1000 0000 0000 0000 0000 0000)
MSB
GAIN23
GAIN22
GAIN21
GAIN20
GAIN19
GAIN18
GAIN17
GAIN16
GAIN15
GAIN14
GAIN13
GAIN12
GAIN11
GAIN10
GAIN9
GAIN8
GAIN7
GAIN6
GAIN5
GAIN4
GAIN3
GAIN2
GAIN1
GAIN0
LSB
GAIN: Gain-calibration bits. The data format is
unsigned binary with 23 bits to the right of the decimal
point and scales the ADC output before being written to
the DATA register. The gain calibration allows full-scale
errors between -VREF/2 and +VREF/2 to be corrected in
unipolar mode and full-scale errors between (+50% x
VREF) and (+200% x VREF) in unipolar or bipolar mode.
The MAX1358B can perform system gain calibration or
self-gain calibration. Self-calibration performs a calibra-
40
tion for offsets in the ADC, and system calibration performs a calibration for the entire signal path. See the
ADC Calibration section for more details.
The ADC input voltage range specifications must always
be obeyed, and the GAIN CAL register effectively scales
the ADC digital output to a full-scale value determined
by the calibration. The usable gain-calibration range is
limited to less than the full GAIN CAL register digitalscaling range by the internal noise of the ADC.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
DAE
DBE
OP1E
X
X
X
DACA9
DACA8
LSB
DACA7
DACA6
DACA5
DACA4
Writing to the DACA_OP output register updates DACA
on the rising SCLK edge of the LSB data bit. The output
voltage can be calculated as follows:
VOUTA = VREF x N/210
where VREF is the reference voltage for the DAC, and N
is the integer value of the DACA output register.
The output buffer is in unity gain. The DACA data is 10
bits long and right justified.
DACA3
DACA2
DACA1
DACA0
DAE: DACA enable bit. Set DAE = 1 to power up the
DACA and the DACA output buffer in the MAX1358B.
DBE: DACB enable bit. Set DBE = 1 to power up the
DACB and the DACB output buffer in the MAX1358B.
This bit is mirrored in the DACB_OP register.
OP1E: OP1 power-enable bit. Set OP1E = 1 to power
up OP1 in the MAX1358B. This bit is mirrored in the
DACB_OP register.
DACA: DACA data bits.
DACB_OP Register (Power-On State: 000X XX00 0000 0000)
MSB
DAE
DBE
OP1E
X
X
X
X
X
X
X
X
X
X
X
X
LSB
Writing to the DACB_OP output register updates DACB
on the rising SCLK edge of the LSB. The output voltage
can be calculated as follows:
VOUTB = VREF x N/210
where VREF is the reference voltage for the DAC, and N
is the integer value of DACB output register. The
output buffer is in unity gain. The DACB data is 10 bits
long and right justified.
X
DAE: DACA enable bit. Set DAE = 1 to power up
DACA and the DACA output buffer in the MAX1358B.
This bit is mirrored in the DACA_OP register.
DBE: DACB enable bit. Set DBE = 1 to power up DACB
and the DACB output buffer in the MAX1358B. This bit is
mirrored in the DACA_OP register.
OP1E: OP1 power-enable bit. Set OP1E = 1 to power
up OP1 in the MAX1358B. This bit is mirrored in the
DACA_OP register.
DACB: DACB data bits.
______________________________________________________________________________________
41
MAX1358B
DACA_OP Register (Power-On State: 000X XX00 0000 0000)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
REF_SDC Register (Power-On State: 0000 0000)
MSB
REFV1
LSB
REFV0
AOFF
AON
The REF_SDC register contains bits to control the reference voltage and signal-detect comparator.
REFV: Reference buffer voltage gain and enable
bits. Enables the output buffer, and sets the gain and
the voltage at the REF pin as shown in Table 10. Poweron state is off to enable an external reference to drive
the REF pin without contention.
AOFF: ADC and DAC/op-amp power-off bit. This bit provides a method for turning off several analog functions
with a single write. Setting AOFF = 1 deasserts the
ADCE in the ADC register and the DAE, DBE, and OP1E
bits in the DACA_OP and DACB_OP registers, powering
down these analog blocks. Setting AOFF = 0 has no
effect. The AON bit has priority when both AON and
AOFF bits are asserted.
Most of the analog functions can be disabled with a
single write to the REF_SDC register by using AOFF,
REFV, and SDCE.
Table 10. Setting the Reference Output
Voltage
REFERENCE
BUFFER GAIN
(V/V)
42
REF OUTPUT
VOLTAGE (V)
REFV1
REFV0
Disabled
Off (High
Impedance
at REF)
0
0
1.0
1.25
0
1
1.638
2.048
1
0
2.0
2.5
1
1
SDCE
TSEL2
TSEL1
TSEL0
AON: ADC and DAC/op-amp power-on bit. This bit provides a method of turning on several analog functions
with a single write. Setting AON = 1 asserts the ADCE
bit in the ADC register and DAE, DBE, and OP1E bits in
the DACA_OP and DACB_OP register, powering up
these blocks. Setting AON = 0 has no effect. The AON
bit has priority when both AON and AOFF bits are
asserted.
Most of the analog functions can be enabled with a single write to the REF_SDC register using AON,
REFV, and SDCE.
SDCE: Signal-detect comparator power-enable bit. Set
SDCE = 1 to power up the signal-detect comparator,
and set SDCE = 0 to power down the signal-detect
comparator. The ADCE bit in the ADC register must be
set to 1 to use the signal-detect comparator.
TSEL: Threshold-select bits. These bits select the
threshold for the signal-detect comparator as shown in
Table 11.
Table 11. Setting the Signal-Detect
Comparator Threshold
NOMINAL
THRESHOLD (mV)
TSEL2
TSEL1
TSEL0
0
0
X
X
50
1
0
0
100
1
0
1
150
1
1
0
200
1
1
1
X = Don’t care.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
ASEC19
ASEC18
ASEC17
ASEC16
ASEC15
ASEC14
ASEC13
ASEC12
ASEC11
ASEC10
ASEC9
ASEC8
ASEC7
ASEC6
ASEC5
ASEC4
LSB
ASEC3
ASEC2
ASEC1
ASEC0
The AL_DAY register stores the second information of
the time-of-day alarm.
ASEC: Alarm-second bits. These 20 bits store
the time-of-day alarm, which corresponds to the lower
20 bits of the RTC second counter or SEC.
Program the time-of-day alarm trigger between 1s to
just over 12 days beyond the current RTC second
counter value in increments of 1s.
Assert the AWE bit in the CLK_CTRL register (see the
CLK_CTRL Register section) to enable writing to the
AL_DAY register. Enabling the time-of-day alarm requires
two writes to the CLK_CTRL register. Write the 20 alarmsecond bits in 3 bytes, MSB first. If CS is raised before
the LSB is written, the alarm write is aborted, and the
X
X
X
X
existing value remains. When the lower 20 bits in the RTC
second counter match the contents of this register, the
alarm triggers and asserts ALD in the STATUS register. It
also asserts an interrupt on the INT pin unless masked by
the MALD bit in the IMSK register. The part enters normal
mode if an alarm triggers while in sleep mode. The timeof-day alarm is intended to trigger single events.
Therefore, once it triggers, in the CLK_CTRL register, the
ADE bit is automatically cleared, disabling the time-ofday alarm. Implement a recurring alarm with repeated
software writes over the serial interface each time the
time-of-day alarm triggers. The time-of-day alarm can
also be programmed to output at the UPIO pins.
When configured this way the MALD bit does not mask
the UPIO alarm output.
______________________________________________________________________________________
43
MAX1358B
AL_DAY Register (Power-On State: 0000 0000 0000 0000 0000 XXXX)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
CLK_CTRL Register (Power-On State: 00X0 1111 0010 1110)
MSB
AWE
ADE
X
RWE
RTCE
OSCE
FLLE
HFCE
LSB
CKSEL2
CKSEL1
CKSEL0
IO32E
The CLK_CTR register contains the control bits for the
RTC alarms and clocks.
AWE: Alarm write-enable bit. Set AWE = 1 to write data
to the AL_DAY register as well as the ADE bit in this
register. When AWE = 0, all writes are prevented to the
AL_DAY register and the ADE bit in this register. A second write to this register is required to change the value
of the ADE bit. The power-on default state is 0.
ADE: Alarm (time-of-day) enable bit. Set ADE = 1 to
enable the time-of-day alarm, and set ADE = 0 to disable the time-of-day alarm. When enabled, the ALD bit
in the STATUS register asserts when the RTC second
counter time matches AL_DAY register. The device
wakes up from sleep to normal mode if not already
awake. The ADE bit can only be written if the AWE = 1
from a previous write. The power-on default state is 0.
RWE: RTC write-enable bit. Set RWE = 1 prior to writing
to the RTC register and the RTCE bit in this register. If
RWE = 0, all writes are prevented to the RTC register
as well as the RTCE bit in this register. The RWE signal
takes effect after the rising edge of the 16th clock;
44
CK32E
CLKE
INTP
WDE
therefore, a second write to this register is required to
change the value of the RTCE bit. The power-on default
state is 0.
RTCE: Real-time-clock enable bit. Set RTCE = 1 to
enable the RTC, and set RTCE = 0 to disable the RTC.
The RTC has a 32-bit second and an 8-bit subsecond
counter. The power-on default state is 1.
OSCE: 32kHz crystal-oscillator enable bit. Set OSCE =
1 to power up the 32kHz oscillator, and set OSCE = 0
to power down the oscillator. The power-on default
state is 1.
FLLE: Frequency-locked-loop enable bit. Set FLLE = 1
to enable the FLL, and set FLLE = 0 to disable the FLL.
If HFCE = 1 and FLLE = 0, the internal high-frequency
oscillator is enabled, but it is not frequency-locked to
the 32kHz clock. When FLLE is asserted, it typically
takes 3.5ms for the high-frequency clock to settle to
within 1% of the 32kHz reference clock frequency.
Switching the FLL on or off with this bit does not cause
high-frequency clock glitching. The power-on default
state is 1.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
External clock frequencies applied to CLK32K are
clock sources to the FLL, charge pump, and the signaldetect comparator. The default power-on state is 0.
power in cases where the high-frequency clock is used
internally but is not needed externally. If HFCE = 0, or if
CLKE = 0, CLK remains low. The power-on default
state is 1.
INTP: Interrupt pin polarity bit. Set INTP = 1 to make
INT an active-high output when asserted, and set INTP
= 0 to make INT an active-low output when asserted.
The power-on default state is 1.
WDE: Watchdog-enable bit. Set WDE = 1 to enable the
watchdog timer, which asserts RESET low within 500ms
if the WATCHDOG register is not written. Set WDE = 0
to disable the watchdog timer. The power-on default
state is 0.
Table 12. Setting the CLK Frequency
CLOCK FREQUENCY
(kHz)
CKSEL2
CKSEL1
CKSEL0
4915.2
0
0
0
2457.6
0
0
1
1228.8
0
1
0
614.4
0
1
1
32.768
1
0
0
16.384
1
0
1
8.192
1
1
0
4.096
1
1
1
CK32E: CLK32K output-buffer enable bit. Set CK32E =
1 to enable the CLK32K output buffer as long as OSCE
= 1 and IO32E = 0; otherwise, the CK32E bit is not
asserted. Set CK32E = 0 to disable the CLK32K output
buffer. The power-on default state is 1.
CLKE: CLK output-buffer enable bit. Set CLKE = 1 to
enable the CLK output buffer. Set CLKE = 0 to disable
the buffer. Disabling the buffer is useful for saving
Table 13. Configuring the CLK32K as an Input or Output
CLK32K
CLK32K
IO32E
32KIN, 32KOUT
RTC, PWM, WDT
CLOCK SOURCE
FLL, C/P, SDC INPUT
SOURCE
ADC CLOCK SOURCE
Output
1
0
XTAL attached
XTAL
XTAL
FLL/HFCLK
Input
0
1
XTAL attached
XTAL
CLK32K
FLL/HFCLK
______________________________________________________________________________________
45
MAX1358B
HFCE: High-frequency-clock enable bit. Set HFCE = 1
to enable the internal high-frequency clock source, and
set HFCE = 0 to disable the high-frequency clock
source.
If HFCE = 1 and CLKE = 1, the internal high-frequency
oscillator is enabled and is present at CLK. The poweron default state is 1.
CKSEL: Clock selection bits. These bits select
the FLL-based output clock frequency at the high-frequency CLK pin as shown in Table 12. The power-on
default state is 001.
IO32E: Input/output 32kHz clock select bit. Set IO32E
= 0 to configure the CLK32K pin as an output, and set
IO32E = 1 to configure the CLK32K pin as an input,
regardless of the signal on the 32KIN pin as shown in
Table 13.
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
RTC Register (Power-On State: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000)
MSB
SEC31
SEC30
SEC29
SEC28
SEC27
SEC26
SEC25
SEC24
SEC23
SEC22
SEC21
SEC20
SEC19
SEC18
SEC17
SEC16
SEC15
SEC14
SEC13
SEC12
SEC11
SEC10
SEC9
SEC8
SEC7
SEC6
SEC5
SEC4
SEC3
SEC2
SEC1
SEC0
LSB
SUB7
SUB6
SUB5
SUB4
The RTC register stores the 40-bit second and subsecond count of the respective time-of-day and system
clocks.
SEC: The second bits store the time-of-day
clock settings. It is a 32-bit binary counter with 1s resolution that can keep time for a span of over 136 years.
Firmware in the µC can translate this time count to units
that are meaningful to the system (i.e., translate to calendar time or as an elapsed time from some predefined
time = 0, such as January 1, 2000). The RTC runs continuously as long as RTCE = 1 (see the CLK_CNTL
Register section) and does not stop for reads or writes.
The counter increments when the subsecond counter
overflows. Set RWE = 1 to enable writing to the RTC
register. After writing to RWE, perform another write
and set RTCE = 1 to enable the RTC. A 40-bit burst
write operation, starting with SEC31 and finishing with
SUB0 is required to set the RTC second and subsecond bits. If CS is brought high before the 40th rising
SCLK edge, the write is aborted and the RTC contents
are unchanged. The RTC register is loaded on the rising SCLK edge of the 40th bit (SUB0). A 40-bit burst
read operation, starting with SEC31 and finishing with
SUB0, is required to retrieve the current RTC second
and subsecond counts. The read command can be
aborted prior to receiving the 40th bit (SUB0) by raising
CS and any RTC data read to that point is valid. When
the read command is received, a snapshot of a valid
RTC second count is latched to avoid reading an erroneous, transitioning RTC value. Due to the asynchronous nature of RTC reads, it is possible to have a
maximum 1s error between the actual and reported
times from the time-of-day clock. To prevent the data
from changing during a read operation, complete reads
46
SUB3
SUB2
SUB1
SUB0
of the RTC register in less than 1ms. The power-on
default state is 0000 0000 hex.
SUB: The subsecond bits store the system clock.
This 8-bit binary counter has 3.9ms resolution (1/256Hz)
and a span of 1s. The subsecond counter increments in
single counts from 00 hex to FF hex before rolling over
again to 00 hex, at which time the RTC second counter
(SEC) increments. The RTC runs continuously
(as long as RTCE = 1) and does not stop for reads or
writes. A 256Hz clock, derived from the 32kHz crystal,
increments this counter. Set the RWE = 1 bit to enable
writing to the RTC register. After writing to RWE, perform
another write, setting RTCE = 1, to enable the RTC. A
40-bit burst write operation, starting with SEC31 and finishing with SUB0, is required to set the RTC second and
subsecond bits. If CS is brought high before the 40th
rising SCLK edge, the write is aborted and the RTC contents are unchanged. The RTC register is loaded on the
rising SCLK edge of the 40th bit (SUB0). A 40-bit burst
read operation, starting with SEC31 and finishing with
SUB0, is required to retrieve the current RTC second
and subsecond counts. The read command can be
aborted prior to receiving the 40th bit (SUB0) by raising
CS, and any RTC data read to that point is valid. When
the read command is received, a snapshot of a valid
RTC second count is latched to avoid reading an erroneous, transitioning RTC value. Due to the asynchronous nature of RTC reads, it is possible to have a
maximum 1s error between the actual and reported
times from the time-of-day clock. To prevent the data
from changing during a read operation, complete reads
of the RTC registers occur in less than 1ms. The poweron default state is 00 hex.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
PWME
FSEL2
FSEL1
FSEL0
SWAH
SWAL
SWBH
SPD1
SPD2
X
X
X
X
X
SWBL
LSB
The PWM_CTRL register contains control bits for the
8-bit PWM.
PWME: PWM-enable bit. Set PWME = 1 to enable the
internal PWM, and set PWME = 0 to disable the internal
PWM. Enable the high-frequency clock before enabling
the PWM when using input clock frequencies above
32.768kHz. The power-on default state is 0.
FSEL: Frequency selection bits. Selects the PWM
input clock frequency as shown in Table 14. The
power-on default is 000.
Table 14. Setting the PWM Frequency
PWM INPUT FREQUENCY*
FSEL2
FSEL1
FSEL0
(kHz)
4915.2**
0
0
0
2457.6**
0
0
1
1228.8**
0
1
0
32.768
0
1
1
8.192
1
0
0
1.024
1
0
1
0.256
1
1
0
0.032
1
1
1
*The lower PWM frequencies are useful for power-supply duty
cycling to conserve battery life and enable a single-battery cellpowered system. The higher frequencies allow reasonably small,
external components for RC filtering when used as a DAC for bias
adjustments.
**When the part is in sleep mode, the HFCLK is shut down. In this
case, PWM frequencies above 32kHz are not available (see
SPWME in the SLEEP_CFG Register section).
X
SWAH: SWA-switch PWM-high control bit. Set SWAH =
1 to enable the PWM output to directly control the SWA
switch. When SWAH = SWAL, the PWM output is disabled from controlling the SWA switch. When SWAH =
1, a PWM high output closes the SWA switch and a
PWM low output opens the SWA switch. The PWM high
output refers to the beginning of the period when the
output is logic-high. See Table 17 for more details. The
power-on default is 0.
SWAL: SWA-switch PWM-low control bit. Set SWAL = 1
to enable the inverted PWM output to directly control
the SWA switch. When SWAH = SWAL, the PWM output
is disabled from controlling the SWA switch. When
SWAL = 1, a PWM low output closes the SWA switch
and a PWM high output opens the SWA switch. The
PWM low output refers to the end of the period when
the output is logic-low. See Table 17 for more details.
The power-on default is 0.
SPD1: SPDT1-switch PWM drive control bit. Set SPD1
= 1 to enable the PWM output to directly control the
SPDT1 switch, and set SPD1 = 0 to disable the PWM
output controlling the SPDT1 switch. The SPDT1
bits, the UPIO pins (if programmed), and the PWM output (if enabled), determine the SPDT1-switch state. See
Table 18 for more details. The power-on default is 0.
SPD2: SPDT2-switch PWM drive control bit. Set SPD2
= 1 to enable the PWM output to directly control the
SPDT2 switch, and set SPD2 = 0 to disable the PWM
output controlling the SPDT2 switch. The SPDT2
bits, the UPIO pins (if programmed), and the PWM output (if enabled), determine the SPDT2-switch state. See
Table 19 for more details. The power-on default is 0.
______________________________________________________________________________________
47
MAX1358B
PWM_CTRL Register (Power-On State: 0000 0000 00XX XXXX)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
PWM_THTP Register (Power-On State: 0000 0000 0000 0000)
MSB
PWMTH7
PWMTH6
PWMTH5
PWMTH4
PWMTH3
PWMTH2
PWMTH1
PWMTH0
LSB
PWMTP7
PWMTP6
PWMTP5
PWMTP4
The PWM_THTP register contains the bits that set the
PWM on-time and period.
PWMTH: PWM time high bits. These bits define
the PWM on (or high)-time and when combined with the
PWMTP bits, they determine the duty cycle and
period. The on-time duty cycle is defined as:
(PWMTH + 1)/(PWMTP + 1)
To get 50% duty cycle, set PWMTH to 126 decimal and PWMTP to 253 decimal. Note that setting
PWMTP to 255 decimal is not valid as the denominator in the above formula becomes 0. A 100% duty
cycle (i.e., always on) is possible with a value of
PWMTH ≥ PWMTP > 0. A 0% duty cycle is
possible by setting PWMTH = 0 or PWME = 0 in
the PWM_CTRL register. If the PWM is selected to drive
the UPIO_ pin(s), the ALH_ bit(s) (UPIO_CTRL register)
determine the on-time polarity at the beginning of the
PWM cycle. If ALH_ = 1, the on-time at the start of the
PWM period causes a logic-high level (DV DD or
CPOUT) at the UPIO_ pin. When ALH_ = 0, it causes a
logic-low level (DGND) during the on-time. When the
PWM output drives the SWA/B switches, the SWA(B)H
or SWA(B)L bits in the PWM_CTRL register determine
which PWM phase closes these switches. The SPDT1
and SPDT2 switches do not have PWM polarity inversion bits (see the SPDT1 and SPDT2 bit
descriptions in the SW_CTRL Register section), but
their effective polarity is set by how the switches are
connected externally. The power-on default is 00 hex.
PWMTP: PWM time period bits. These bits control the PWM output period defined. The PWM output
period is defined as:
PWMTP3
PWMTP2
PWMTP1
WATCHDOG Register (Power-On State: N/A)
Writing to the WATCHDOG register address sets the
watchdog timer to 0ms. If the watchdog is enabled
(WDE = 1) and the WATCHDOG register is not written
to before the 750ms expiration, RESET asserts low for
250ms and the watchdog timer restarts at 0ms when
the watchdog timer is enabled. There are no data bits
for this register, and the watchdog timer is reset on the
rising edge of SCLK during the ADR0 bit in the
WATCHDOG register address control byte. Figure 17
shows an example of watchdog timing.
NORM_MD Register (Power-On State: N/A)
Exit sleep mode and enter normal mode by writing to
the NORM_MD register. The specific normal-mode
state of all circuit blocks is set by the user, who must
configure the individual power-enable bits before entering sleep mode (Table 15). There are no data bits for
this register, and normal mode begins on the rising
edge of SCLK during the ADR0 bit in the NORM_MD
register address control byte.
SLEEP Register (Power-On State: N/A)
Enter sleep mode by writing to the SLEEP register. This
low-power state overrides most of the normal powercontrol bits. Table 15 shows which functions are off,
which functions are unaffected (ADE, RTCE, LSDE, and
HYSE), and which functions are controlled by special
sleep-mode bits (SOSCE, SCK32E, and SPWME) while
in sleep mode. There are no data bits for this register,
and sleep mode begins on the rising edge of SCLK
during the ADR0 bit in the SLEEP register address control byte.
(PWMTP + 1)/(PWM input frequency)
Set the PWM input frequency by selecting the
FSEL bits as described in Table 14. The poweron default is 00 hex.
48
PWMTP0
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
REGISTER
NAME
ADC
DACA_OP,
DACB_OP
REF_SDC
CLK_CTRL
PWM_CTRL
PS_VMONS
TEMP_CTRL
UPIO_CTRL
CIRCUIT BLOCK
DESCRIPTION
POR DEFAULT
NORMAL MODE
SLEEP
ADC
ADCE = 0
ADCE
OFF
DACA
DAE = 0
DAE
OFF
DACB
DBE = 0
DBE
OFF
OP1
OP1E = 0
OP1E
OFF
Reference Buffer Gain and
Enable
REFV = 00
REFV
OFF
Signal-Detect Comparator
SDCE = 0
SDCE
OFF
Time-of-Day Alarm Enable
ADE = 0
ADE
ADE
RTC
RTCE = 1
RTCE
RTCE
CK32 XTAL Oscillator
OSCE = 1
OSCE
SOSCE
CK32 Output Buffer
CK32E = 1
CK32E
SCK32E
High-Frequency Clock
HFCE = 1
HFCE
OFF
High-Frequency Clock Output
Buffer
CLKE = 1
CLKE
OFF
FLL Enable
FLLE = 1
FLLE
OFF
Watchdog Timer
WDE = 0
WDE
OFF
PWM
PWME = 0
PWME
SPWME
Linear Regulator
LDOE = 0
LDOE
OFF
Charge-Pump Doubler
CPE = 0
CPE
OFF
CPOUT Voltage Monitor
CPDE = 0
CPDE
OFF
1.8V DVDD Monitor
LSDE = 1
LSDE
LSDE
1.8V Monitor Hysteresis
HYSE = 0
HYSE
HYSE
Temperature Sense Source
IMUX = 00
IMUX
OFF
UPIO_ Function
UP_MD = 0 hex
UP_MD
UP_MD
UPIO_ Pullup
PUP_ = 1
PUP_
PUP_
UPIO_ Supply Voltage
SV_ = 0
SV_
SV_
UPIO_ Assertion Level
ALH_ = 0
ALH_
ALH_
______________________________________________________________________________________
MAX1358B
Table 15. Normal-Mode and Sleep-Register Summary
49
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
SLEEP_CFG Register (Power-On State: 1100 XXXX)
MSB
SLP (ADR0)
LSB
SOSCE
SCK32E
SPWME
SHDN
The SLEEP_CFG register allows users to program specific behavior for the 32kHz oscillator, buffer, and PWM
in sleep mode. It also contains a sleep-control bit (SLP)
to enable sleep mode.
SLP (ADR0): Sleep bit. The SLP bit is the LSB in the
SLEEP_CFG address control byte. Set SLP = 1 to
assert the SHDN bit and enter sleep mode. Writing the
register with SLP = 0 or reading with SLP = 0 or
SLP = 1 has no effect on the SHDN bit.
SOSCE: Sleep-mode 32kHz crystal oscillator enable
bit. SOSCE = 1 enables the 32kHz oscillator in sleep
mode, and SOSCE = 0 disables it in sleep mode,
regardless of the state of the OSCE bit. The power-on
default is 1.
SCK32E: Sleep-mode CK32K-pin output-buffer enable
bit. SCK32E = 1 enables the 32kHz output buffer in
sleep mode, and SCK32E = 0 disables it in sleep
mode, regardless of the state of the CK32E bit. The
power-on default is 1.
X
X
X
X
SPWME: Sleep-mode PWM enable bit. SPWME = 1
enables the internal PWM in sleep mode, and
SPWME = 0 disables it in sleep mode, regardless of the
state of the PWME bit.
Input frequencies are limited to 32.768kHz or lower
since the high-frequency clock is disabled in sleep
mode. SOSCE must be asserted to have 32kHz available as an input to the PWM. The power-on default is 0.
SHDN: Shutdown bit. This bit is read only. SHDN is
asserted by writing to the SLEEP register address or by
writing to the SLEEP_CFG register with SLP = 1. When
SHDN is asserted, the device is in sleep mode even if
the SLEEP or SLEEP function on the UPIO is deasserted. The SHDN bit is deasserted by writing to the
NORM_MD register or by other defined events. Events
that cause SHDN to be deasserted are a day alarm or
an edge on the UPIO wake-up pin causing wake-up to
be asserted. The power-on default is 0.
RESET
32K
DIVIDEBY-8192
WDE
D
Q
CK
Q
Q
D
4Hz
CK
Q
R
R
POR
WDW
WATCHDOG TIMER
750ms
4Hz CLOCK
2-BIT COUNTER
X
0
1
2
0
1
0
1
2
3
0
1
2
0
SPI WRITES
RESET
WDE = 1
WATCHDOG
ADDRESS
WATCHDOG
ADDRESS
WATCHDOG
ADDRESS
250ms
Figure 17. Watchdog Timer Architecture
50
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
UP4MD3
LSB
UP4MD2
UP4MD1
UP4MD0
The UPIO4_CTRL register configures the UPIO4 pin
functionality.
UP4MD: UPIO4-mode selection bits. These bits
configure the mode for the UPIO4 pin. See Table 16 for
a detailed description. The power-on default is 0 hex.
PUP4: Pullup UPIO4 control bit. Set PUP4 = 1 to enable
a weak pullup resistor on the UPIO4 pin, and set PUP4
= 0 to disable it. The pullup resistor is connected to
either DVDD or CPOUT as programmed by the SV4 bit.
The pullup is enabled only when UPIO4 is configured as
an input. Open-drain behavior can be simulated at
UPIO4 by setting the mode to GPO with LL4 = 0 and by
changing the mode to GPI with PUP4 = 0, allowing
external high pullup. The power-on default is 1.
SV4: Supply-voltage UPIO4 selection bit. Set SV4 = 0
to select DVDD as the supply voltage for the UPIO4 pin,
and set SV4 = 1 to select CPOUT as the supply voltage. The selected supply voltage applies to all modes
for the UPIO4 pin. The power-on default is 0.
PUP4
SV4
ALH4
LL4
ALH4: Active logic-level assertion high UPIO4 bit. Set
ALH4 = 0 to define the input or output assertion level
for UPIO4 as low except when in GPI and GPO modes.
Set ALH4 = 1 to define the input or output assertion
level as high. For example, asserting ALH4 defines the
UPIO4 output signal as ALARM, while deasserting
ALH4 defines it as ALARM. Similarly, asserting ALH4
defines the UPIO4 input signal as WU, while deasserting ALH4 defines it as WU. The power-on default is 0.
LL4: Logic-level UPIO4 bit. When UPIO4 is configured
as GPO, LL4 = 0 sets the output to a logic-low and LL4
= 1 sets the output to a logic-high. A read of LL4
returns the voltage level at the UPIO4 pin at the time of
the read, regardless of how it is programmed. The
power-on default is 0.
UPIO3_CTRL Register (Power-On State: 0000 1000)
MSB
UP3MD3
LSB
UP3MD2
UP3MD1
UP3MD0
The UPIO3_CTRL register configures the UPIO3 pin
functionality.
UP3MD: UPIO3-mode selection bits. These bits
configure the mode for the UPIO3 pin. See Table 16 for
a detailed description. The power-on default is 0 hex.
PUP3: Pullup UPIO3 control bit. Set PUP3 = 1 to enable
a weak pullup resistor on the UPIO3 pin, and set PUP3
= 0 to disable it. The pullup resistor is connected to
either DVDD or CPOUT as programmed by the SV3 bit.
The pullup is enabled only when UPIO3 is configured as
an input. Open-drain behavior can be simulated at
UPIO3 by setting the mode to GPO with LL3 = 0 and by
changing the mode to GPI with PUP3 = 0, allowing
external high pullup. The power-on default is 1.
SV3: Supply-voltage UPIO3 selection bit. Set SV3 = 0
to select DVDD as the supply voltage for the UPIO3 pin,
and set SV3 = 1 to select CPOUT as the supply voltage. The selected supply voltage applies to all modes
for the UPIO3 pin. The power-on default is 0.
PUP3
SV3
ALH3
LL3
ALH3: Active logic-level assertion high UPIO3 bit. Set
ALH3 = 0 to define the input or output assertion level
for UPIO3 as low except when in GPI and GPO modes.
Set ALH3 = 1 to define the input or output assertion
level as high. For example, asserting ALH3 defines the
UPIO3 output signal as ALARM, while deasserting
ALH3 defines it as ALARM. Similarly, asserting ALH3
defines the UPIO3 input signal as WU, while deasserting ALH3 defines it as WU. The power-on default is 0.
LL3: Logic-level UPIO3 bit. When UPIO3 is configured
as GPO, LL3 = 0 sets the output to a logic-low and LL3
= 1 sets the output to a logic-high. A read of LL3
returns the voltage level at the UPIO3 pin at the time of
the read, regardless of how it is programmed. The
power-on default is 0.
______________________________________________________________________________________
51
MAX1358B
UPIO4_CTRL Register (Power-On State: 0000 1000)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
UPIO2_CTRL Register (Power-On State: 0000 1000)
MSB
UP2MD3
LSB
UP2MD2
UP2MD1
UP2MD0
The UPIO2_CTRL register configures the UPIO2 pin
functionality.
UP2MD: UPIO2-mode selection bits. These bits
configure the mode for the UPIO2 pin. See Table 16 for
a detailed description. The power-on default is 0 hex.
PUP2: Pullup UPIO2 control bit. Set PUP2 = 1 to enable
a weak pullup resistor on the UPIO2 pin, and set PUP2
= 0 to disable it. The pullup resistor is connected to
either DVDD or CPOUT as programmed by the SV2 bit.
The pullup is enabled only when UPIO2 is configured as
an input. Open-drain behavior can be simulated at
UPIO2 by setting the mode to GPO with LL2 = 0 and by
changing the mode to GPI with PUP2 = 0, allowing
external high pullup. The power-on default is 1.
SV2: Supply-voltage UPIO2 selection bit. Set SV2 = 0
to select DVDD as the supply voltage for the UPIO2 pin,
and set SV2 = 1 to select CPOUT as the supply voltage. The selected supply voltage applies to all modes
for the UPIO2 pin. The power-on default is 0.
PUP2
SV2
ALH2
LL2
ALH2: Active logic-level assertion high UPIO2 bit. Set
ALH2 = 0 to define the input or output assertion level
for UPIO2 as low except when in GPI and GPO modes.
Set ALH2 = 1 to define the input or output assertion
level as high. For example, asserting ALH2 defines the
UPIO2 output signal as ALARM, while deasserting
ALH2 defines it as ALARM. Similarly, asserting ALH2
defines the UPIO2 input signal as WU, while deasserting ALH2 defines it as WU. The power-on default is 0.
LL2: Logic-level UPIO2 bit. When UPIO2 is configured
as GPO, LL2 = 0 sets the output to a logic-low and LL2
= 1 sets the output to a logic-high. A read of LL2
returns the voltage level at the UPIO2 pin at the time of
the read, regardless of how it is programmed. The
power-on default is 0.
UPIO1_CTRL Register (Power-On State: 0000 1000)
MSB
UP1MD3
LSB
UP1MD2
UP1MD1
UP1MD0
The UPIO1_CTRL register configures the UPIO1 pin
functionality.
UP1MD: UPIO1-mode selection bits. These bits
configure the mode for the UPIO1 pin. See Table 16 for
a detailed description. The power-on default is 0 hex.
PUP1: Pullup UPIO1 control bit. Set PUP1 = 1 to enable
a weak pullup resistor on the UPIO1 pin, and set PUP1
= 0 to disable it. The pullup resistor is connected to
either DVDD or CPOUT as programmed by the SV1 bit.
The pullup is enabled only when UPIO1 is configured as
an input. Open-drain behavior can be simulated at
UPIO1 by setting the mode to GPO with LL1 = 0 and by
changing the mode to GPI with PUP1 = 0, allowing
external high pullup. The power-on default is 1.
SV1: Supply-voltage UPIO1 selection bit. Set SV1 = 0
to select DVDD as the supply voltage for the UPIO1 pin,
and set SV1 = 1 to select CPOUT as the supply volt-
52
PUP1
SV1
ALH1
LL1
age. The selected supply voltage applies to all modes
for the UPIO1 pin. The power-on default is 0.
ALH1: Active logic-level assertion high UPIO1 bit. Set
ALH1 = 0 to define the input or output assertion level
for UPIO1 as low except when in GPI and GPO modes.
Set ALH1 = 1 to define the input or output assertion
level as high. For example, asserting ALH1 defines the
UPIO1 output signal as ALARM, while deasserting
ALH1 defines it as ALARM. Similarly, asserting ALH1
defines the UPIO1 input signal as WU, while deasserting ALH1 defines it as WU. The power-on default is 0.
LL1: Logic-level UPIO1 bit. When UPIO1 is configured
as GPO, LL1 = 0 sets the output to a logic-low and LL1
= 1 sets the output to a logic-high. A read of LL1
returns the voltage level at the UPIO1 pin at the time of
the read, regardless of how it is programmed. The
power-on default is 0.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
UP4MD,
UP3MD,
UP2MD, UP1MD
MODE
MAX1358B
Table 16. UPIO Mode Configuration
DESCRIPTION
0
0
0
0
GPI
General-purpose digital input. Active edges detected by UPR_ or UPF_
status register bits. ALH_ has no effect with this setting.
0
0
0
1
GPO
General-purpose digital output. Logic level set by LL_ bit. ALH_ has no
effect with this setting.
0
0
1
0
SWA or SWA
Digital input. DAC A buffer switch control. See the SWA bit description in
the SW_CTRL Register section.
0
0
1
1
SWB or SWB
Digital input. DAC B buffer switch control. See the SWB bit description in
the SW_CTRL Register section.
0
1
0
0
SPDT1 or SPDT1
Digital input. SPDT1 switch control. See the SPDT1 bit description in the
SW_CTRL Register section.
0
1
0
1
SPDT2 or SPDT2
Digital input. SPDT2 switch control. See the SPDT2 bit description in the
SW_CTRL Register section.
0
SLEEP or SLEEP
Sleep-mode digital input. Overrides power-control register and puts the
part into sleep mode when asserted. The clock buffers must be powered
down separately. When deasserted, power mode is determined by the
SHDN bit.
WU or WU
Wake-up digital input. Asserted edge clears SHDN bit.
Reserved
Reserved. Do not use these settings.
0
1
1
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
PWM digital output. Signal defined by the PWM_CTRL register. PWM on
(or high or “1”); assertion level defined by the ALH_ bit. When PWM is
disabled (PWME = 0), the UPIO pin idles high (DVDD or CPOUT) if
ALH = 1, and low (DGND) if ALH = 0.
1
0
1
1
PWM or PWM
1
1
0
0
SHDN or SHDN
Power-supply shutdown digital output. Equivalent to SHDN bit. Power-on
default of GPI with pullup ensures initial power-supply turn-on when UPIO
is connected to a power supply with a SHDN input.
1
1
0
1
AL_DAY or AL_DAY
RTC alarm digital output. Asserts for time-of-day alarm events; equivalent
to ALD in STATUS register.
1
1
1
0
Reserved
1
1
1
1
DRDY or DRDY
Reserved. Do not use these settings.
ADC data-ready digital output. Asserts when analog-to-digital conversion
or calibration completes. Not masked by MADD bit.
Note: When multiple UPIO inputs are configured for the same input function, the inputs are ORed together.
______________________________________________________________________________________
53
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
UPIO_SPI Register (Power-On State: 0000 XXXX)
MSB
LSB
UP4S
UP3S
UP2S
UP1S
X
The UPIO_SPI pass-through control register bits map
the serial interface signals to the UPIO pins, allowing
the DAS to drive other devices at CPOUT or DVDD voltage levels, depending on the SV_ bit setting found in
the UPIO_CTRL register. Individual bits are provided to
set only the desired UPIO inputs to the SPI passthrough mode. This mode becomes active when CS is
driven high to complete the write to this register, and
remains active as long as CS stays high (i.e., multiple
pass-through writes are possible). The SPI passthrough mode is deactivated immediately when CS is
pulled low for the next DAS write.
WRITE TO DAS TO ENABLE SPI MODE
X
X
UP4S: UPIO4 SPI pass-through-mode enable bit. A
logic 1 maps the inverted CS signal to the UPIO4 pin.
Therefore, UPIO4 is low (near DGND) when SPI passthrough mode is active, and is high (near DV DD or
CPOUT) when the mode is inactive. A logic 0 disables
the UPIO4 SPI pass-through mode. The power-on
default is 0.
UP3S: UPIO3 SPI pass-through-mode enable bit. A
logic 1 maps the SCLK signal to UPIO3 (directly with no
inversion), while a logic 0 disables the UPIO3 SPI passthrough mode. The power-on default is 0.
UP2S: UPIO2 SPI pass-through-mode enable bit. A
logic 1 maps the DIN signal to UPIO2 (directly with no
inversion), while a logic 0 disables the UPIO2 SPI passthrough mode. The power-on default is 0.
UP1S: UPIO1 SPI pass-through-mode enable bit. A
logic 1 maps the UPIO1 input signal to DOUT (directly
with no inversion), while a logic 0 disables the UPIO1
SPI pass-through mode. The power-on default is 0.
The UPIO_ state (both before and after the SPI passthrough mode) is set by the UP_MD and LL_ bits.
When a UPIO is configured for SPI pass-through mode
and the CS is high, UPR_, UPF_, and LL_ continue to
detect UPIO_ edges, which can still generate interrupts.
See Figure 18 for an SPI pass-through timing diagram.
CS
X
NORMAL WRITE TO DAS
WRITE THROUGH DAS TO UPIO DEVICE
SCLK
DIN
DN
DN-1 DN-2 DN-3
D3
D2
D1
D0
EN
EN-1
EN-2
EN-3
DOUT
X
X
X
X
E3
E2
E1
E0
D7
D6
D5
D4
D3
UPIO4
SET BY UPIO4_CTRL REGISTER
SET BY UPIO4_CTRL REGISTER
UPIO3
SET BY UPIO3_CTRL REGISTER
SET BY UPIO3_CTRL REGISTER
UPIO2
SET BY UPIO2_CTRL REGISTER
UPIO1
SET BY UPIO1_CTRL REGISTER
EN
EN-1
EN-2
EN-3
X
X
X
X
SET BY UPIO2_CTRL REGISTER
E3
E2
E1
E0
SET BY UPIO1_CTRL REGISTER
Figure 18. SPI Pass-Through Timing Diagram
54
D2
______________________________________________________________________________________
D1
D0
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
SWA
LSB
SWB
SPDT11
SPDT10
The switch-control register controls the two SPDT
switches (SPDT1 and SPDT2) and the DACA output
buffer SPST switch (SWA). Control this switch by the
serial bits in this register, by any of the UPIO pins that
are enabled for that function, or by the PWM.
SWA: DACA output buffer SPST-switch A control bit.
The SWA bit, the UPIO inputs (if configured), and the
PWM (if configured) control the state of the SWA switch
as shown in Table 17. The UPIO_ states of 0 and 1 in the
table correspond to respective deasserted and asserted
logic states as defined by the ALH_ bit of the
UPIO_CTRL register. If a UPIO is not configured for this
mode, its value applied to the table is 0. The PWM
states of 0 and 1 in the table correspond to the respective PWM off (or low) and on (or high) states defined by
the SWAH and SWAL bits (see the PWM_CTRL Register
section). If the PWM is not configured for this mode, its
value applied to the table is 0. The power-on default is 0.
SWB: DACB output buffer SPST-switch B control bit.
The SWB bit, the UPIO inputs (if configured), and the
PWM (if configured) control the state of the SWB switch
as shown in Table 18. The UPIO_ states of 0 and 1 in the
table correspond to respective deasserted and asserted
logic states as defined by the ALH_ bit (see the
UPIO_CTRL Register section). If a UPIO is not configured for this mode, its value applied to the table is 0.
The PWM states of 0 and 1 in the table correspond to
the respective PWM off (or low) and on (or high) states
defined by the SWBH and SWBL bits (see the
PWM_CTRL Register section). If the PWM is not configured for this mode, its value applied to the table is 0.
The power-on default is 0.
SPDT1: Single-pole double-throw switch 1 control bits. The SPDT1 bits, the UPIO pins (if configured), and the PWM (if configured) control the state of
the switch as shown in Table 18. The UPIO_ states of 0
and 1 in the table correspond to respective deasserted
and asserted logic states as defined by the ALH_ bit of
the UPIO_CTRL register. If a UPIO is not configured for
this mode, its value applied to Table 18 is 0. The PWM
states of 0 and 1 in Table 18 correspond to the respective PWM off (low) and on (high) states defined by the
SPD1 bit in the PWM_CTRL register. If the PWM is not
configured for this mode, its value applied to Table 18
is 0. The power-on default is 00.
SPDT21
SPDT20
X
X
Table 17. SWA States
SW_ BIT*
UPIO_*
PWM*
SW_ SWITCH STATE
0
0
0
X
X
1
Switch open
Switch closed
X
1
X
Switch closed
1
X
X
Switch closed
X = Don’t care.
*Switch SW_ control is effectively an OR of the SW_ bit, UPIO_
pins, and PWM.
Table 18. SPDT Switch 1 States
SPDT1
UPIO_* PWM* SPDT1 SWITCH STATE
0
0
0
0
SNO1 open, SNC1 open
0
X
0
X
X
1
SNO1 closed, SNC1 closed
1
X
0
1
SNO1 closed, SNC1 closed
X
X
SNO1 closed, SNC1 closed
1
0
0
0
SNC1 closed, SNO1 open
1
X
X
1
SNC1 open, SNO1 closed
1
X
1
X
SNC1 open, SNO1 closed
1
1
X
X
SNC1 open, SNO1 closed
X = Don’t care.
*Switch SPDT1 control is effectively an OR of the SPDT10 bit, the
UPIO_ pins, and the PWM output. The SPDT11 bit determines if
the switches open and close together or if they toggle.
Table 19. SPDT Switch 2 States
SPDT2 UPIO_* PWM* SPDT2 SWITCH STATE
0
0
0
0
SNO2 open, SNC2 open
0
X
X
1
SNO2 closed, SNC2 closed
0
X
1
X
SNO2 closed, SNC2 closed
0
1
X
X
SNO2 closed, SNC2 closed
1
0
0
0
SNC2 closed, SNO2 open
1
X
X
1
SNC2 open, SNO2 closed
1
X
1
X
SNC2 open, SNO2 closed
1
1
X
X
SNC2 open, SNO2 closed
X = Don’t care.
*Switch SPDT2 control is effectively an OR of the SPDT20 bit, the
UPIO_ pins, and the PWM output. The SPDT21 bit determines if
the switches open and close together or if they toggle.
______________________________________________________________________________________
55
MAX1358B
SW_CTRL Register (Power-On State: 0000 00XX)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
SPDT2: Single-pole double-throw switch 2 control
bits. The SPDT2 bits, the UPIO pins (if configured), and the PWM (if configured) control the state of
the switch as shown in Table 19. The UPIO_ states of 0
and 1 in the table correspond to respective deasserted
and asserted logic states as defined by the ALH_ bit in
the UPIO_CTRL register. If a UPIO is not configured for
this mode, its value applied to Table 19 is 0. The PWM
states of 0 and 1 in Table 19 correspond to the respective PWM off (low) and on (high) states defined by the
SPD2 bit in the PWM_CTRL register. If the PWM is not
configured for this mode, its value applied to Table 19 is
0. The power-on default is 00.
TEMP_CTRL Register (Power-On State: 0000 XXXX)
MSB
IMUX1
LSB
IMUX0
IVAL1
IVAL0
X
X
X
X
The temperature-sensor control register controls the
internal and external temperature measurement.
IMUX: Internal current-source MUX bits. Selects
the pin to be driven by the internal current sources as
shown in Table 20. The power-on default is 00.
IVAL: Internal current-source value bits. Selects
the value of the internal current source as shown in
Table 21. The power-on default is 00.
Table 20. Selecting Internal Current Source
Table 21. Setting the Current Level
CURRENT SOURCE
Disabled
Internal temperature sensor
AIN1
AIN2
56
IMUX1
0
0
1
1
IMUX0
0
1
0
1
CURRENT
TYPICAL CURRENT (µA)
IVAL1
IVAL0
I1
I2
I3
I4
4
60
64
120
0
0
1
1
0
1
0
1
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MSB
MLDVD
MLCPD
MADO
MSDC
MCRDY
MADD
MALD
X
LSB
MUPR4
MUPR3
MUPR2
MUPR1
The IMSK register determines which bits of the STATUS
register generate an interrupt on INT. The bits in this
register do not mask output signals routed to UPIO
since the output signals are masked by disabling that
UPIO function.
MLDVD: LDVD status bit mask. Set MLDVD = 0 to
enable the LDVD status bit interrupt to INT, and set
MLDVD = 1 to mask the LDVD status bit interrupt. The
power-on default value is 1.
MLCPD: LCP status bit mask. Set MLCPD = 0 to
enable the LCP status bit interrupt to INT, and set
MLCPD = 1 to mask the LCP status bit interrupt. The
power-on default value is 1.
MADO: ADO status bit mask. Set MADO = 0 to enable
the ADO status bit interrupt to INT, and set MADO = 1
to mask the ADO status bit interrupt. The power-on
default value is 1.
MSDC: SDC status bit mask. Set MSDC = 0 to enable
the SDC status bit interrupt to INT, and set MSDC = 1
to mask the SDC status bit interrupt. The power-on
default value is 1.
MCRDY: CRD status bit mask. Set MCRDY = 0 to
enable the CRDY status bit interrupt to INT, and set
MUPF4
MUPF3
MUPF2
MUPF1
MCRDY = 1 to mask the CRDY status bit interrupt. The
power-on default value is 0.
MADD: ADD status bit mask. Set MADD = 0 to enable
the ADD status bit interrupt to INT, and set MADD = 1
to mask the ADD status bit interrupt. The power-on
default value is 1.
MALD: ALD status bit mask. Set MALD = 0 to enable
the ALD status bit interrupt to INT, and set MALD = 1 to
mask the ALD status bit interrupt. The power-on default
value is 1.
MUPR: UPR status bits mask. Set MUPR_ =
0 to enable the UPR_ status bit interrupt to INT, and set
MUPR_ = 1 to mask the UPR_ status bit interrupt. (_ =
1, 2, 3, or 4 and corresponds to the UPIO1, UPIO2,
UPIO3, or UPIO4 pins, respectively.) The power-on
default value is F hex.
MUPF: UPF status bits mask. Set MUPF_ =
0 to enable the UPF_ status bit interrupt to INT, and set
MUPF_ = 1 to mask the UPF_ status bit interrupt. (_ = 1,
2, 3, or 4 and corresponds to the UPIO1, UPIO2,
UPIO3, or UPIO4 pins, respectively.) The power-on
default value is F hex.
PS_VMONS Register (Power-On State: 0010 01XX)
MSB
LDOE
LSB
CPE
LSDE
CPDE
HYSE
RSTE
X
X
This register is the power-supply and voltage monitors
control register.
disable the DV DD low-supply-voltage detector. The
power-on default value is 1.
LDOE: Low-dropout linear-regulator enable bit. Set
LDOE = 1 to enable the low-dropout linear regulator to
provide the internal source voltage for the charge
pump. Set LDOE = 0 to disable the LDO, allowing an
external drive to the charge-pump input through REG.
The power-on default value is 0.
CPE: Charge-pump enable bit. Set CPE = 1 to enable the
charge-pump doubler, and set CPE = 0 to disable the
charge-pump doubler. The power-on default value is 0.
LSDE: DV DD low-supply voltage-detector powerenable bit. Set LSDE = 1 to enable the +1.8V (DVDD)
low-supply-voltage detector, and set LSDE = 0 to
CPDE: CPOUT low-supply voltage-detector powerenable bit. Set CPDE = 1 to enable the +2.7V CPOUT
low-supply voltage-detector comparator, and set CPDE
= 0 to disable the CPOUT low-supply voltage-detector
comparator. The power-on default value is 0.
HYSE: DVDD low-supply voltage-detector hysteresisenable bit. Set HYSE = 1 to set the hysteresis for the
+1.8V (DVDD) low-supply-voltage detector to +200mV,
and set HYSE = 0 to set the hysteresis to +20mV. On initial
power-up, the hysteresis is +20mV and can be programmed to 200mV once RESET goes high. Once programmed to +200mV, the DVDD falling threshold is +1.8V
nominally and the rising threshold is +2.0V nominally. The
______________________________________________________________________________________
57
MAX1358B
IMSK Register (Power-On State: 1111 011X 1111 1111)
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
hysteresis helps eliminate chatter when running directly off
unregulated batteries. If DVDD falls below +1.3V (typ), the
power-on reset circuitry is enabled and the HYSE bit is
deasserted setting the hysteresis back to +20mV. The
power-on default is 0.
RSTE: RESET output enable bit. Set RSTE = 1 to
enable RESET to be controlled by the +1.8V DVDD lowsupply-voltage detector, and set RSTE = 0 to disable
this control. The power-on default is 1.
STATUS Register (Power-On State: 0000 000X 0000 0000)
MSB
LDVD
LCPD
ADOU
SDC
CRDY
ADD
ALD
X
UPR4
UPR3
UPR2
UPR1
UPF4
UPF3
UPF2
UPF1
LSB
The STATUS register contains the status bits of events in
various system blocks. Any status bits not masked in the
IMSK register cause an interrupt on INT. Some of the
status bit setting events (GPI, WAKEUP, ALARM, DRDY)
can be directed to UPIO_ to provide multiple µC interrupt inputs. There are no specific mask bits for the UPIO
interrupt signals since the bits are effectively masked by
selecting a different function for UPIO. The STATUS bits
always record the triggering event(s), even for masked
bits, which do not generate an interrupt on INT. It is possible to set multiple STATUS bits during a single INT
interrupt event. Clear all STATUS bits except for ADD
and ADOU by reading the STATUS register. During a
STATUS register read, INT deasserts when the first
STATUS data bit (LDVD) reads out (9th rising SCLK) and
remains deasserted until shortly after the last STATUS
data bit (~15ns). At this point, INT reasserts if any
STATUS bit is set during the STATUS register read. If the
STATUS register is partially read (i.e., the read is aborted
midway), none of the STATUS bits are cleared. New
events occurring during a STATUS register read, or
events that persist after reading the STATUS bits result in
another interrupt immediately after the STATUS register
read finishes. This is a read-only register.
LDVD: Low DVDD voltage-detector status bit. LDVD = 1
indicates DVDD is below the +1.8V threshold; otherwise
LDVD = 0. LDVD clears during the STATUS register
read as long as the condition does not persist.
Otherwise, the LDVD bit reasserts immediately. If the
DVDD low voltage detector is disabled, LDVD = 0. The
power-on default is 0.
LCPD: Low CPOUT voltage-detector status bit. LCPD =
1 indicates CPOUT is below the +2.7V threshold; otherwise LCPD = 0. LCPD clears during the STATUS register read as long as the condition does not persist.
Otherwise the LCPD bit reasserts immediately. LCPD =
0 when the CPOUT low voltage detector is disabled.
The power-on default is 0.
58
ADOU: ADC overflow/underflow status bit. ADOU = 1
indicates an ADC underflow or overflow condition in the
current ADC result. New conversions that are valid
clear the ADOU bit. ADOU = 0 when the ADC data is
valid or the ADC is disabled (ADCE = 0). An underflow
condition occurs when the ADC data is theoretically
less than 0000 hex in unipolar mode and less than
8000 hex in bipolar mode. An overflow condition occurs
when the ADC data is theoretically greater than FFFF
hex in unipolar mode and greater than 7FFF hex in
bipolar mode. Use this bit to determine the validity of
an ADC result at the maximum or minimum code values
(i.e., 0000 hex or FFFF hex for unipolar mode and 8000
hex and 7FFF hex for bipolar mode). The power-on
default is 0. Reading the STATUS register does not
clear the ADOU bit.
SDC: Signal-detect comparator status bit. When
SDC = 1, the positive input to the signal-detect comparator exceeds the negative input plus the programmed
threshold voltage. The SDC bit clears during the STATUS
register read unless the condition remains true. The SDC
bit also deasserts when the signal-detect comparator
powers down (SDCE = 0). The power-on default is 0.
CRDY: High-frequency-clock ready status bit.
CRDY = 1 indicates a locked high-frequency clock to
the 32kHz reference frequency by the FLL. The CRDY
bit clears during the STATUS register read. This bit only
asserts after power-up or after enabling the FLL using
the FLLE bit. The power-on default is 0.
ADD: ADC-done status bit. ADD = 1 indicates a completed ADC conversion or calibration. Clear the ADD bit
by reading the appropriate ADC data, offset, or gain-calibration registers. The ADC status bit also clears when a
new ADC result updates to the data or calibration registers (i.e., it follows the assertion level of the UPIO =
DRDY signal). Reading the STATUS register does not
clear this bit. This bit is equivalent to the DRDY signal
available through UPIO_. The power-on default is 0.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Applications Information
Analog Filtering
The internal digital filter does not provide rejection
close to the harmonics of the modulator sample frequency. However, due to high oversampling ratios in
the MAX1358B, these bands typically occupy a small
fraction of the spectrum and most broadband noise is
filtered. Therefore, the analog filtering requirements in
front of the MAX1358B are considerably reduced compared to a conventional converter with no on-chip filtering. In addition, because the device’s common-mode
rejection (60dB) extends out to several kHz, the common-mode noise susceptibility in this frequency range
is substantially reduced.
Depending on the application, provide filtering prior to the
MAX1358B to eliminate unwanted frequencies the digital
filter does not reject. Providing additional filtering in some
applications ensures that differential noise signals outside
the frequency band of interest do not saturate the analog
modulator.
When placing passive components in front of the
MAX1358B, ensure a low enough source impedance to
prevent introducing gain errors to the system. This configuration significantly limits the amount of passive antialiasing filtering that can be applied in front of the
MAX1358B. See Table 3 for acceptable source impedances.
Power-On Reset or Power-Up
After a power-on reset, the DVDD voltage supervisor is
enabled and all UPIOs are configured as inputs with
pullups enabled. The internal oscillators are enabled and
are output at CLK and CLK32K once the DVDD voltage
supervisor is cleared and the subsequent timeout period
has expired. All interrupts are masked except CRDY.
Figure 19 illustrates the timing of various signals during
initial power-up, sleep mode, and wake-up events. The
ADC, charge pump, internal reference, op amp(s), DAC,
and switches are disabled after power-up.
Power Modes
Two power modes are available for the MAX1358B:
sleep and normal mode. In sleep mode, all functional
blocks are powered down except the serial interface,
data registers, internal bandgap, wake-up circuitry (if
enabled), DVDD voltage supervisor (if enabled), and
the 32kHz oscillator (if enabled), which remain active.
See Table 15 for details of the sleep-mode and normalmode power states of the various internal blocks.
Each analog block can be shut down individually
through its respective control register with the exception of the bandgap reference.
Sleep Mode
Sleep mode is entered one of three ways:
• Writing to the SLEEP register address. The result is
the SHDN bit is set to 1.
• Asserting the SLEEP or SLEEP function on a UPIO
(SLEEP takes precedence over software writes or
wake-up events). The SHDN bit is unaffected.
• Asserting the SHDN bit by writing SLP = 1 in the
SLEEP_CFG register.
Entering sleep mode is an OR function of the UPIO or
SHDN bit. Before entering sleep mode, configure the
normal mode conditions.
Exit sleep mode and enter normal mode by one of the
following methods:
• With the SHDN bit = 0, deassert the SLEEP or
SLEEP function on UPIO, only if SLEEP or SLEEP
function is used for entering sleep mode.
______________________________________________________________________________________
59
MAX1358B
ALD: Alarm (day) status bit. ALD = 1 when the value
programmed in ASEC in the AL_DAY register
matches SEC in the RTC register. Clear the ALD
bit by reading the STATUS register or by disabling the
day alarm (ADE = 0). The power-on default is 0.
UPR: User-programmable I/O rising-edge status
bits. UPR_ = 1 indicates a rising edge on the respective UPIO_ pin has occurred. Clear UPR_ by reading
the STATUS register. Rising edges are detected independent of UPIO_ configuration, providing the ability to
capture and record rising input (e.g., WU) or output
(e.g., PWM) edge events on the UPIO_. Set the appropriate mask to determine if the edge will generate an
interrupt on INT. If the UPIO_ is configured as an output, INT provides confirmation that an intended rising
edge output occurred and has reached the desired
DVDD or CPOUT level (i.e., was not loaded down externally). The power-on default is 0.
UPF: User-programmable I/O falling-edge status
bit. UPF_ = 1 indicates a falling edge on the respective
UPIO_ has occurred. Clear UPF_ by reading the
STATUS register. Falling edges are detected independent of UPIO_ configuration, providing the ability to capture and record falling input (e.g., WU) or output (e.g.,
PWM) edge events on the UPIO_. Set the appropriate
mask to determine if that edge should generate an interrupt on the INT pin. If the UPIO is configured as an output, INT provides confirmation that an intended falling
edge output occurred at the pin and it reached the
desired DGND level. The power-on default is 0.
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
2
AVDD
INITIAL POWER, WAKE-UP, AND SLEEP
XTAL BETWEEN 32KIN AND 32KOUT PIN
1.8V
1
0V
2
DVDD
1.8V
1
0V
POR
HI
LO
OSCE = 1
SOSCE = 1
OSCE = 1
XIN, XOUT HI
(32kHz) LO
CK32E = 1
RESET HI
(OPEN DRAIN) LO
INTERNAL
EXTERNAL
OUTPUT DISABLED,
BUT
PULLED LOW
HI
INTERNAL
LOW DVDD DETECTOR LO
CK32E = 1
SCK32E = 0
BUFFER DISABLED
HI
CK32K
(32kHz) LO
OUTPUT ENABLED
UPIO (WU) HI
(INT. PULLUP) LO
tWU
tDPU
HI
UPIO (SHDN)
INTERNAL
LO
tDPD
CLK
HI
INTERNAL
LO
tDFON
INTERNAL HI
CRDY
HFCE = 1, FLLE = 1 LO
tDFON
tDFOF
IF FLLE = 0, CRDY WILL
STAY LOW, DFON = 0
tDFI
INT
tDFI
HI
LO
PWME = 0
UPIO (PWM) HI
CONNECTED TO POWER
SUPPLY SHDN PIN LO
INTERNAL
DRDY
DOUT
SPWME = 1
POWER SUPPLY OFF
HI
LO
HI
LO
HI
CS
LO
THREE-STATED
SLEEP
WRITE
HI
SCLK,
DIN LO
Figure 19. Initial Power-Up, Sleep Mode, and Wake-Up Timing Diagram with AVDD > 1.8V
60
PWME = 0
POWER SUPPLY OFF
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
VREF/GAIN
VREF/GAIN
BINARY OUTPUT CODE
VREF
(GAIN x 65,536)
1 LSB =
VREF/GAIN
0111 1111 1111 1101
BINARY OUTPUT CODE
0111 1111 1111 1110
1111 1111 1111 1101
VREF
x2
(GAIN x 65,536)
0000 0000 0000 0001
0000 0000 0000 0000
1111 1111 1111 1111
VREF/GAIN
FULL-SCALE TRANSITION
1 LSB =
VREF/GAIN
0111 1111 1111 1111
1111 1111 1111 1110
1111 1111 1111 1100
0000 0000 0000 0011
0000 0000 0000 0010
1000 0000 0000 0010
0000 0000 0000 0001
1000 0000 0000 0001
0000 0000 0000 0000
0
1
2
65,533
3
MAX1358B
VREF/GAIN
1111 1111 1111 1111
65,535
1000 0000 0000 0000
-32,768
-32,766
INPUT VOLTAGE (LSB)
-1
0
+1
+32,765
+32,767
INPUT VOLTAGE (LSB)
Figure 20. ADC Unipolar Transfer Function
Figure 21. ADC Bipolar Transfer Function
• With the SLEEP or SLEEP function deasserted on
UPIO, clear the SHDN bit by writing to the normalmode register address control byte.
• With the SLEEP or SLEEP function deasserted,
assert WU or WU (wake-up) function on UPIO.
• With the SLEEP or SLEEP function deasserted, the
day alarm triggers.
MAX1358B
FBA
OUTA
DAC A
REF
FBB
Wake-Up
A wake-up event, such as an assertion of a UPIO configured as WU or a time-of-day alarm causes the
MAX1358B to exit sleep mode, if in sleep mode. A
wake-up event in normal mode results only in a wake-up
event being recorded in the STATUS register.
RESET
The RESET output pulls low for any one of the following
cases: power-on reset, DV DD monitor trips and
RSTE = 0, watchdog timer expires, crystal oscillator is
attached, and 32kHz clock not ready.
The RESET output can be turned off through the RSTE
bit in the PS_VMONS register, causing DVDD low supply voltage events to issue an interrupt or poll through
the LDVD status bit. This allows brownout detection
µCs that operate with DVDD < 1.8V.
Driving UPIO Outputs to AVDD Levels
UPIO outputs can be driven to AVDD levels in systems
with separate AVDD and DVDD supplies. Disable the
charge-pump doubler by setting CPE = 0 in the
PS_VMONS register, and connect the system’s analog
supply to AVDD and CPOUT. Setting UPIO outputs to
drive to CPOUT results in AVDD-referenced logic levels.
DAC B
OUTB
Figure 22. DAC Unipolar Output Circuit
Supply Voltage Measurement
The AVDD supply voltage can be measured with the
ADC by reversing the normal input and reference signals. The REF voltage is applied to one multiplexer
input, and AGND is selected in the other. The AVDD
signal is then switched in as the ADC reference voltage
and a conversion is performed. The AVDD value can
then be calculated directly as:
VAVDD = (VREF x Gain x 65,536)/N
where VREF is the reference voltage for the ADC, Gain
is the PGA gain before the ADC, and N is the ADC
result. Note the AVDD voltage must be greater than the
gained-up REF voltage (AVDD > VREF x Gain). This
measurement must be done in unipolar mode.
______________________________________________________________________________________
61
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
VREF
FBA
MAX1358B
R1
R2
10kΩ
+3.3V
FB_
10kΩ
VOUT
OUTA
DAC A
DAC_
OUT_
REF
FBB
-3.3V
10kΩ
MAX1358B
10kΩ
DAC B
R2 = R1
VREF = 1.25V
OUTB
VREF = 1.25V
Figure 23. DAC Unipolar Rail-to-Rail Output Circuit
Figure 24. DAC Bipolar Output Circuit
In unipolar mode, the output code ranges from 0 to
65,535 for inputs from zero to full-scale. In bipolar
mode, the output code ranges from -32,768 to +32,767
for inputs from negative full-scale to positive full-scale.
Power Supplies
AVDD and DVDD provide power to the MAX1358B. The
AVDD powers up the analog section, while the DVDD powers up the digital section. The power supply for both AVDD
and DVDD ranges from +1.8V to +3.6V. Both AVDD and
DVDD must be greater than +1.8V for device operation.
AVDD and DVDD can connect to the same power supply.
Bypass AVDD to AGND with a 10µF electrolytic capacitor
in parallel with a 0.1µF ceramic capacitor, and bypass
DVDD to DGND with a 10µF electrolytic capacitor in parallel with a 0.1µF ceramic capacitor. For improved performance, place the bypass capacitors as close to the device
as possible.
ADC Transfer Functions
Figures 20 and 21 provide the ADC transfer functions
for unipolar and bipolar mode. The digital output code
format is binary for unipolar mode and two’s complement for bipolar mode. Calculate 1 LSB using the following equations:
1 LSB (Unipolar Mode) = VREF/(Gain x 65,536)
1 LSB (Bipolar Mode) = ±2VREF/(Gain x 65,536)
DAC Unipolar Output
For a unipolar output, the output voltages and the reference have the same polarity. Figure 22 shows the
unipolar output circuit of the MAX1358B, which is also
the typical operating circuit for the DAC. Table 22 lists
some unipolar input codes and their corresponding
output voltages.
For larger output swing, see Figure 23. This circuit
shows the output amplifiers configured with a closedloop gain of +2V/V to provide 0 to 2.5V full-scale range
with the 1.25V reference.
DAC Bipolar Output
The MAX1358B DAC output can be configured for
bipolar operation using the application circuit in
Figure 24:
⎡⎛ 2N ⎞
⎤
VOUT = VREF ⎢⎜
⎟ − 1⎥
⎝
⎠
1024
⎣
⎦
where VREF equals the reference voltage at REF and
Gain equals the PGA gain.
where N is the decimal value of the DAC’s binary input code.
Table 23 shows digital codes (offset binary) and corresponding output voltages for Figure 24 assuming
R1 = R2.
Table 22. Unipolar Code
Table 23. Bipolar Code
DAC CONTENTS
MSB
LSB
1111 1111 11
1000 0000 01
1000 0000 00
0111 1111 11
0000 0000 01
0000 0000 00
62
ANALOG OUTPUT
+VREF (1023/1024)
+VREF (513/1024)
+VREF (512/1024) = +VREF/2
+VREF (511/1024)
+VREF (1/1024)
0
DAC CONTENTS
MSB
LSB
1111 1111 11
1000 0000 01
1000 0000 00
0111 1111 11
0000 0000 01
0000 0000 00
ANALOG OUTPUT
+VREF (511/512)
+VREF (1/512)
0
-VREF (1/512)
-VREF (511/512)
-VREF (512/512) = -VREF
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
Input Multiplexer
The mux inputs can range between AGND and AVDD.
However, when the internal temperature sensor is
enabled, AIN1 and AIN2 cannot exceed 0.7V. This
necessitates additional circuitry to divide down the
input signal. See Figure 26 for an example circuit that
divides down backlight VDD to work properly with the
AIN1 pin.
Optical Reflectometry Application with
Dual LED and Single Photodiode
Figure 27 illustrates the MAX1358B in a complete optical reflectometry application with two transmitting LEDs
and one receiving photodiode. The LEDs transmit light
at a specific wavelength onto the sample strip, and the
photodiode receives the reflections from the strip. Set
the DAC to provide appropriate bias currents for the
LEDs. Always keep the photodiodes reverse-biased or
zero-biased. SPDT1 and SPDT2 switch between the
two LEDs.
Electrochemical Sensor Operation
The MAX1358B family interface with electrochemical
sensors. The 10-bit DAC with the force-sense buffers
have the flexibility to connect to many different types of
sensors. An external precision resistor completes the
transimpedance amplifier configuration to convert the
current generated by the sensor to a voltage measurement using the ADC. The induced error from this source
is negligible due to FBA’s extremely low input bias current. Internally, the ADC can differentially measure
directly across the external transimpedance resistor,
RF, eliminating any errors due to voltages drifting over
time, temperature, or supply voltage.
Temperature Measurement with
Two Remote Sensors
Use two diode-connected 2N3904 transistors for external temperature sensing in Figure 29. Select AIN1 and
AIN2 through the positive and negative mux, respectively. For internal temperature sensor measurements,
set MUXP to 0111, and set MUXN to 0000.
The analog input signals feed through a PGA to the
ADC for conversion.
The MAX1358B integrated PWM is available for LCD
bias control, sensor-bias voltage trimming, buzzer drive,
and duty-cycled sleep-mode power-control schemes.
Figure 30 shows the MAX1358B performing LCD bias
control. A sensor-bias voltage trimming application is
shown in Figure 31. Figures 33 and 34 show the PWM
circuitry being used in a single-ended and differential
piezoelectric buzzer-driving application.
ADC Calibration
Internal to the MAX1358B, the ADC is 24 bits and is
always in bipolar mode. The OFFSET CAL and GAIN
CAL data is also 24 bits. The conversion to unipolar and
the gain are performed digitally. The default values for
the OFFSET CAL and GAIN CAL registers in the
MAX1358B are 00 0000h and 80 0000h, respectively.
The calibration works as follows:
ADC = (RAW - OFFSET) x Gain x PGA
where ADC is the conversion result in the DATA register,
RAW is the output of the decimation filter internal to the
MAX1358B, OFFSET is the value stored in the OFFSET
CAL register, Gain is the value stored in the GAIN CAL
register, and PGA is the selected PGA gain found in the
ADC register as GAIN. In unipolar mode, all negative values return a zero result and an additional gain of 2
is added.
BACKLIGHT
VDD
VBATT2
CMOS CLOCK
(0 TO DVDD)
100kΩ
VBATT1
32KIN
UPIO1
GPIOn
100kΩ
MAX1358B
MAX1358B
BATTVCHECK
x2
< 0.6125V
NOTE:
GPIOn IS LOW = LED ON,
HIGH-Z = LED OFF
AIN1
VREF = 1.25V
μP
Figure 25. Clocking with a CMOS Signal
Figure 26. Input Multiplexer
______________________________________________________________________________________
63
MAX1358B
Clocking with a CMOS Signal
A CMOS signal can be used to drive 32KIN if it is divided down. Figure 25 is an example circuit, which works
well.
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
VCP
SERIAL-PORT INTERFACE
TXD
RXD
VSS
VSS
μC
VBAT
EEPROM
VSS
MOSI
SI
MISO
SO
SCK
SCK
CS1
CS
VCC
GND
VSS
MAX1358B
VCP
BDOUT
UPIO2
DIN
LCD MODULE
BDIN
UPIO1
BSCLK
UPIO3
DOUT
BCS2
UPIO4
SCLK
CS2
MEM
UP
DOWN
INPUT
RESET
INPUT
INPUT
INPUT
X2IN
32KIN
CS2
VSS
CS
RESET
INT
HIGH-FREQUENCY MICRO CLOCK
32kHz MICRO CLOCK
CLK
IN1-
CLK32K
VSS
IN1+
AVDD
VBAT
OUT1
DVDD
VDD
2 AAA OR
1 LITHIUM
COIN CELL
VSS
VSS
1nF
SNO2
ADC
TEST
STRIP
SCM2
VSS
AGND
SNC2
VSS
DGND
PWM
VSS
AMBIENT LIGHT
AIN1
AIN2
DACA
LED SOURCES
VCP
OUTA
32KIN
LED
SWA
FBA
SNO1
32.768kHz
VCP
LED
SCM1
32KOUT
DVDD
SNC1
LINEAR
REG
REG
CF+
VSS
CF-
CHARGEPUMP
DOUBLER
REF
BG
CPOUT
VCP
VSS
VSS
VSS
Figure 27. Optical Reflectometry Application with Dual LED and Single Photodiode
64
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
μC
VCP
LCD GLASS
COM
SEG
LCDBIAS
RX_WAKEUP
SERIAL-PORT INTERFACE
RXD
VSS
LCD
DRIVERS
VSS
BUZ_HI
PIEZO
ALARM
BUZ_LO
VBAT
EEPROM
VSS
MOSI
SI
MISO
SO
SCK
SCK
CS1
CS
VCC
GND
VSS
MAX1358B
CPOUT
UPIO2
DIN
TXD
DOUT
SCLK
CS2
MEM
UP
DOWN
CS2
CPOUT
PWM
CS
UPIO4
INPUT
RESET
RESET
OUTA
INPUT
INPUT
INT
SWA
CLK
FBA
INPUT
X2IN
32KIN
HIGH-FREQUENCY MICRO CLOCK
32kHz MICRO CLOCK
LCDBIAS
STRIP INSERTED
VSS
TEST
STRIP
CLK32K
VSS
AVDD
VBAT
DVDD
VDD
RX_WAKEUP
UPIO1
UPIO3
VSS
DACA
OUTB
2 AAA OR
1 LITHIUM
COIN CELL
SWB
FBB
VSS
AGND
VSS
ADC
DGND
DACB
SNO1
SCM1
SNC1
32KIN
OUT1
32.768kHz
IN132KOUT
DVDD
IN1+
LINEAR
REG
BG
REF
REG
CF+
VSS
CFCPOUT
VCP
VSS
CHARGEPUMP
DOUBLER
SNO2
SCM2
SNC2
AIN1
REMOTE TEMPERATUREMEASUREMENT DIODE
VSS
AIN2
VSS
Figure 28. Electrochemical Meter Application Circuit (Traditional and Counter Configuration)
______________________________________________________________________________________
65
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
For self-calibration, the offset value is the RAW result
when the inputs are shorted internally and the gain value
is 1/(RAW - OFFSET) with the reference connected to the
input. This is done automatically when these modes are
selected. The self-offset and gain calibration corrects for
errors internal to the ADC and the results are stored and
used automatically in the OFFSET CAL and GAIN CAL
registers. For best results, use the ADC in the same configuration as the calibration. This pertains to conversion
rate only because the PGA gain and unipolar/bipolar
modes are performed digitally.
For system calibration, the offset and gain values correct for errors in the whole signal path including the
internal ADC and any external circuits in the signal
path. For the system calibration, a user-provided zeroinput condition is required for the offset calibration and
a user-provided full-scale input is required for the gain
calibration. These values are automatically written to
the OFFSET CAL and GAIN CAL registers. The order of
the calibrations should be offset followed by gain.
The offset correction value is in two’s complement. The
default value is 000000h, 00...00b, or 0 decimal.
The gain correction value is an unsigned binary number
with 23 bits to the right of the decimal point. The largest
number is therefore 1.1111...1b = 2 - 2-23 and the smallest is 0.000...0b = 0, although it does not make sense to
use a number smaller than 0.1000...0b = 0.5. The default
value is 800000h, 1.000...0b or 1 decimal.
Changing the offset or gain calibration values does not
affect the value in the DATA register until a new conversion has completed. This applies to all the mode bits
for PGA gain, unipolar/bipolar, etc.
Grounding and Layout
For best performance, use a PCB with separate analog
and digital ground planes.
Design the PCB so that the analog and digital sections
are separated and confined to different areas of the
board. Join the digital and analog ground planes at one
point. If the DAS is the only device requiring an AGND-toDGND connection, connect planes to the AGND pin of the
DAS. In systems where multiple devices require AGND-toDGND connections, the connection should still be made
at only one point. Make the star ground as close as possible to the MAX1358B.
Avoid running digital lines under the device because
these may couple noise onto the device. Run the ana-
66
log ground plane under the MAX1358B to minimize
coupling of digital noise. Make the power-supply lines
to the MAX1358B as wide as possible to provide lowimpedance paths and reduce the effects of glitches on
the power-supply line.
Shield fast-switching signals such as clocks with digital
ground to avoid radiating noise to other sections of the
board. Avoid running clock signals near the analog
inputs. Avoid crossover of digital and analog signals.
Good decoupling is important when using high-resolution ADCs. Decouple all analog supplies with 10µF
capacitors in parallel with 0.1µF HF ceramic capacitors
to AGND. Place these components as close to the
device as possible to achieve the best decoupling.
Crystal Layout
Follow basic layout guidelines when placing a crystal
on a PCB with a DAS to avoid coupled noise:
1) Place the crystal as close as possible to 32KIN and
32KOUT. Keeping the trace lengths between the
crystal and inputs as short as possible reduces the
probability of noise coupling by reducing the length
of the “antennae”. Keep the 32KIN and 32KOUT
lines close to each other to minimize the loop area
of the clock lines. Keeping the trace lengths short
also decreases the amount of stray capacitance.
2) Keep the crystal solder pads and trace width to
32KIN and 32KOUT as small as possible. The larger these bond pads and traces are, the more likely
it is that noise will couple from adjacent signals.
3) Place a guard ring (connect to ground) around the
crystal to isolate the crystal from noise coupled
from adjacent signals.
4) Ensure that no signals on other PCB layers run
directly below the crystal or below the traces to
32KIN and 32KOUT. The more the crystal is isolated from other signals on the board, the less likely it
is that noise will be coupled into the crystal.
Maintain a minimum distance of 5mm between any
digital signal and any trace connected to 32KIN or
32KOUT.
5) Place a local ground plane on the PCB layer immediately below the crystal guard ring. This helps to
isolate the crystal from noise coupling from signals
on other PCB layers.
Note: The ground plane must be in the vicinity of the
crystal only and not on the entire board.
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
AIN1
MUX
PGA
16-BIT ADC
REF
AGND
2N3904
AV = 1, 2, 4, 8
AIN2
MAX1358B
MUX
AGND
AV = 1, 1.638, 2
2N3904
TEMP
SENSOR
1.25V
REF
CREF
REF
Figure 29. Temperature Measurement with Two Remote Sensors
Parameter Definitions
INL
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line is either a best-straight-line fit or a line drawn
between the end points of the transfer function, once offset and gain errors have been nulled. INL for the
MAX1358B is measured using the end-point method.
DNL
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A DNL
error specification of greater than -1 LSB guarantees no
missing codes and a monotonic transfer function.
Gain Error
Gain error is the amount of deviation between the measured full-scale transition point and the ideal full-scale
transition point.
Common-Mode Rejection
Common-mode rejection (CMR) is the ability of a
device to reject a signal that is common to both input
terminals. The common-mode signal can be either an
AC or a DC signal or a combination of the two. CMR is
often expressed in decibels.
Power-Supply Rejection Ratio (PSRR)
Power-supply rejection ratio (PSRR) is the ratio of the
input supply change (in volts) to the change in the
converter output (in volts). It is typically measured in
decibels.
______________________________________________________________________________________
67
MAX1358B
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
DVDD CPOUT
SV_
CPOUT
MUX
100kΩ
200kΩ
UPIO_
PWM
0.01μF
μC
(1.8V
TO
2.6V)
100kΩ
EN_
SEG
ALH_
LCD
DRIVERS
100kΩ
n
LCD
COM m
100kΩ
Figure 30. LCD Contrast-Adjustment Application
~1.25V
REF
~19kHz
VOLTAGE
RIPPLE < 1mV
350kΩ
MAX1358B
SNO1
SCM1
PWM
240kΩ
~0.3V
SNC1
SPDT1
0.1μF
60kΩ
AGND
IN1+
OUT1
IN1IT
TRANSDUCER
0.300V (±1mV)
Figure 31. Sensor-Bias Voltage Trim Application
68
______________________________________________________________________________________
16-Bit, Data-Acquisition System with ADC, DACs,
UPIOs, RTC, Voltage Monitors, and Temp Sensor
MAX1358B
VDD
AVDD
DVDD
MAX1358B
DVDD
< 10μA
CPOUT
MUX
VBATT
10MΩ
VDD
VOUT
VIN
SV_
100μF
POWER SUPPLY
μC
UPIO_
PWM
SHDN
PSCTL
ON-TIME
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