19-0009; Rev 2; 8/95
ANUAL
N KIT M EET
ATIO
SH
EVALU
S DATA
OLLOW
F
±18-Bit ADC with Serial Interface
____________________________Features
o
Low Supply Current:
60µA (Normal Operation)
1µA (Sleep-Mode Operation)
o
±0.006% FSR Accuracy at 16 Conv/sec
o
Low Noise: 15µV
RMS
o
Serial I/O Interface with Programmed Output for
Mux and PGA
o
Performs up to 100 Conv/sec
o
±2pA Input Current
o
50Hz/60Hz Rejection
_______________General Description
The MAX132 is a CMOS, 18-bit plus sign, serial-output,
analog-to-digital converter (ADC). Multi-slope integra-
tion provides high-resolution conversions in less time
than standard integrating ADCs, allowing operation up
to 100 conversions per second. Low conversion noise
provides guaranteed operation with ±512mV full-scale
input range (2µV/LSB). A simple 4-wire serial interface
connects easily to all common microprocessors, and
twos-complement output coding simplifies bipolar mea-
surements. Typical supply current is only 60µA and is
reduced to 1µA in sleep mode. Four serially pro-
grammed digital outputs can be used to control an
external multiplexer or programmable-gain amplifier.
The MAX132 comes in 24-pin narrow DIP and wide SO
packages, and is available in commercial and extend-
ed temperature grades.
High resolution, compact size, and low power make this
device ideal for data loggers, weigh scales, data-acqui-
sition systems, and panel meters.
MAX132
______________Ordering Information
PART
MAX132CNG
MAX132CWG
MAX132C/D
MAX132ENG
MAX132EWG
MAX132MRG
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
24 Narrow Plastic DIP
24 Wide SO
Dice*
24 Narrow Plastic DIP
24 Wide SO
24 Narrow CERDIP**
________________________Applications
Remote Data Acquisition
Battery-Powered Instruments
Industrial Process Control
Transducer-Signal Measurement
Pressure, Flow, Temperature, Voltage
Current, Resistance, Weight
* Contact factory for dice specifications.
** Contact factory for availability and processing to MIL-STD-883.
________________Functional Diagram
__________________Pin Configuration
TOP VIEW
CREF-
CS
SCLK
EOC
DIN
DOUT
CREF+
V+
602k
+5V
CS 1
DIN 2
DOUT 3
24 V+
23 BUF OUT
22 INT OUT
21 INT IN
BUF OUT
INT OUT
INT IN
REF+
REF-
4.7nF
SCLK 4
OSC2 5
OSC1 6
P0 7
±512mV INPUT
P1 8
P2 9
P3 10
EOC 11
DGND 12
MAX132
20 CREF-
19 CREF+
18 REF+
17 REF-
16 AGND
15 IN LO
14 IN HI
13 V-
MAX132
P0
P1
P2
P3
OSC1
AGND
IN LO
IN HI
V-
DGND
OSC2
-5V
DIP/SO
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
±18-Bit ADC with Serial Interface
MAX132
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
V+ to DGND ..............................................-0.3V < V+ < +6.0V
V- to DGND ................................................+0.3V < V- < -9.0V
V+ to V- ............................................................................+15V
Analog Input Voltage (any input).....................................V+ to V-
Digital Input Voltage .....................(DGND - 0.3V) to (V+ + 0.3V)
Continuous Power Dissipation
Narrow Plastic DIP (derate 8.70mW/°C above +70°C)....478mW
Wide SO (derate 11.76mW/°C above +70°C)..............647mW
Narrow CERDIP (derate 12.50mW/°C above +70°C) ..688mW
Operating Temperature Ranges
MAX132C_ _ .......................................................0°C to +70°C
MAX132E_ _ ....................................................-40°C to +85°C
MAX132MRG .................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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
(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, R
INT
= 602kΩ, C
INT
= 0.0047µF, C
REF
= 0.1µF,
f
CLK
= 32,768Hz, 60Hz mode, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
ACCURACY
Resolution
Zero Error
Integral Nonlinearity
Rollover Error
Conversion Time
Input Voltage Range
CONDITIONS
(Note 1)
V
IN
HI = 0V
(Notes 2, 3)
(Note 4)
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= +25°C
T
A
= T
MIN
to T
MAX
63
±2
±12
±0.009
±0.25
±512
±10
±250
±0.032
±0.50
±3.0
±3.1
±1.5
±5
5.5
-4.5
±0.0061
±0.0168
±0.0061
±0.0168
125
-65
-60
10
-10
±2
0
±0.0015
0
MIN
TYP
MAX
±18
±0.0076
±0.0168
±0.006
±0.010
±0.032
UNITS
Bits
% of FSR
% of FSR
% of FSR
ms
mV
pA
% of FSR
V
% of FSR
µV
ppm/°C
ppm/°C
V
V
% of FSR
% of FSR
µA
µA
µA
µA
µA
µA
f
CLK
= 32.768Hz
IN HI to IN LO, for specified accuracy
T
A
= +25°C
Leakage Current
IN HI, IN LO
T
A
= T
MIN
to T
MAX
V
CM
= ±500mV
Common-Mode Rejection Ratio IN HI = IN LO
V
CM
= ±3.0V
Common-Mode Range
IN HI = IN LO
Read-Zero 50Hz/60Hz Range
RMS Noise
T
A
= +25°C
Zero-Reading Drift
(Note 3)
Scale Factor Temp. Coefficient (Note 3)
POWER REQUIREMENTS
Positive Supply Voltage
Negative Supply Voltage
T
A
= +25°C
V
IN
HI = 400mV, V- = -5.0V,
Positive Supply Rejection
4.5V
≤
V+
≤
5.5V
T
A
= T
MIN
to T
MAX
T
A
= +25°C
V
IN
HI = 400mV, V- = 5.0V,
Negative Supply Rejection
-5.5V
≤
V-
≤
-4.5V
T
A
= T
MIN
to T
MAX
Positive Supply Current
Digital input = 0V or V+
Negative Supply Current
Digital input = 0V or V+
Digital Ground Supply Current Digital input = 0V or V+
Positive Sleep-Mode Current
Digital input = 0V or V+
Negative Sleep-Mode Current
Digital input = 0V or V+
Digital Ground Sleep-Mode
Current
Digital input = 0V or V+
15
±0.15
4.5
-5.5
±0.003
±0.003
±0.003
±0.003
60
-35
-25
1
-1
0
2
_______________________________________________________________________________________
±18-Bit ADC with Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, R
INT
= 602kΩ, C
INT
= 0.0047µF, C
REF
= 0.1µF,
f
CLK
= 32,768Hz, 60Hz mode, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
DIGITAL SECTION
DOUT, I
OUT
= -1mA
Output High
V
OH
DOUT, I
OUT
= -100µA
EOC, P0–P3, I
OUT
= -100µA
Output Low
Input High
Input Low
Input Current
Input Capacitance
V
OL
V
IH
V
IL
I
IN
C
IN
DOUT, I
OUT
= 1.6mA
EOC, P0–P3, I
OUT
= 100µA
Referred to DGND, 4.5V
≤
V+
≤
5.5V, CS, DIN, SCLK
Referred to DGND, 4.5V
≤
V+
≤
5.5V, CS, DIN, SCLK
CS, DIN, SCLK, and DOUT when three-stated
CS, DIN, SCLK, and DOUT when three-stated
±10
2.4
0.8
±500
5
3.5
4.0
4.0
4.3
4.5
4.7
0.1
0.1
0.4
0.4
V
V
V
nA
pF
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX132
INTERFACE TIMING
(Test Circuit of Figure 1, Figure 2, V+ = 5V, V- = -5V, DGND = AGND = 0V, T
A
= +25°C, unless otherwise noted.) (Note 3)
PARAMETER
CS Lead Time
CS Lag Time
S
CLK
High Time
S
CLK
Low Time
CS High Pulse Width
DIN to SCLK Setup Time
DIN to SCLK Hold Time
DOUT Access Time from Three-State
Data Valid
DOUT Disable Time to Three-State
Delay to P0–P3 High
Delay to P0–P3 Low
Note 1:
Note 2:
Note 3:
Note 4:
SYMBOL
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
10
t
11
t
12
See Figure 4
230
230
See Figure 3
CONDITIONS
MIN
500
400
400
300
1
0
200
320
60
320
350
350
TYP
MAX
UNITS
ns
ns
ns
ns
µs
ns
ns
ns
ns
ns
ns
ns
±18-bit accuracy achieved by averaging multiple conversions.
Maximum deviation from best straight-line fit.
Guaranteed by design, not tested.
Difference in reading for equal positive and negative inputs near full scale.
_______________________________________________________________________________________
3
±18-Bit ADC with Serial Interface
MAX132
__________________________________________Typical Operating Characteristics
ERROR vs. COMMON-MODE
INPUT VOLTAGE (V
IN
LO–AGND)
MAX132-01
50Hz/60Hz READ-ZERO OFFSET
vs. VREF
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
50Hz MODE
0
0.5
1.0
VREF (V)
1.5
2.0
60Hz MODE
MAX132-02
50Hz/60Hz READ-ZERO OFFSET
vs. TEMPERATURE
1.4
60Hz MODE, VREF = 545mV
1.2
1.0
0.8
0.6
0.4
0.2
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
50Hz MODE, VREF = 655mV
MAX132-03
0.05
0
ERROR (% OF FSR)
-0.05
-0.10
-0.15
-0.20
-0.25
-0.30
-4
-3
-2
-1
0
1
2
3
COMMON-MODE VOLTAGE (V)
4
IN HI = IN LO
4.5
READ-ZERO OFFSET (% OF FSR)
1.6
READ-ZERO OFFSET (% OF FSR)
SUPPLY CURRENT
vs. CRYSTAL FREQUENCY
MAX132-04
FULL-SCALE ROLLOVER ERROR
vs. VREF
MAX132-05
NOISE vs. NUMBER
OF SAMPLES AVERAGED
MAX132-06
140
120
SUPPLY CURRENT (µA)
100
80
60
40
20
0
-20
-40
0
50
100
150
200
250
300
V-
V+
0.10
ROLLOVER ERROR (% OF FSA)
0.08
20
15
0.06
NOISE (µV
RMS
)
10
0.04
0.02
5
0
350
0
0.5
1.0
1.5
2.0
2.5
CRYSTAL FREQUENCY (kHz)
VREF (V)
0
0
10
20
30
40
50
NUMBER OF SAMPLES AVERAGED
______________________________________________________________Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
CS
DIN
DOUT
SCLK
OSC2
OSC1
P0
P1
FUNCTION
CHIP SELECT Input has 3 functions: 1) When low, selects IC for communication; 2) on rising edge, loads
input shift register data into one of the command registers; 3) on falling edge, loads data from one of the
output registers into the output shift register. When CS is high, DOUT is high impedance.
Serial Data In, D7 first bit in. Data is clocked into the register on the rising edge of SCLK.
Serial Data Out, D7 first bit out. Data is clocked out at the falling edge of SCLK. High impedance when CSis high.
Serial Clock Input. On SCLK’s rising edge, data is shifted into the internal shift register through DIN. On
SCLK’s falling edge, data is clocked out of DOUT.
Oscillator Output 2 is normally connected to a 32,768Hz crystal. Do not connect with external clock source.
Oscillator Input 1 is normally connected to a 32,768Hz crystal, or may be connected to an external clock.
User-programmable output bit 0—programmed through the serial port.
User-programmable output bit 1—programmed through the serial port.
4
_______________________________________________________________________________________
±18-Bit ADC with Serial Interface
_________________________________________________Pin Description (continued)
PIN
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
NAME
P2
P3
EOC
DGND
V-
IN HI
IN LO
AGND
REF-
REF+
CREF+
CREF-
INT IN
INT OUT
BUF OUT
V+
FUNCTION
User-programmable output bit 2—programmed through the serial port.
User-programmable output bit 3—programmed through the serial port.
End of Conversion Output goes high at end of conversion.
Digital Ground—power-supply return
Negative Supply, nominally -5V
Positive Analog Input
Negative Analog Input
Analog Ground
Negative Reference Input
Positive Reference Input
Positive Reference Capacitor connection
Negative Reference Capacitor connection
Integrator Input. Connect the integration capacitor between INT IN and INT OUT.
Integrator Output. To minimize noise, this pin should drive the capacitor’s outside foil (negative end).
Buffer-Amplifier Output drives the integrator resistor.
Positive Supply, nominally +5V
MAX132
0.1µF
20
CREF-
1
4
11
2
3
CS
SCLK
EOC
DIN
DOUT
REF+
REF-
7
8
9
10
19
CREF+
V+
24
23
22
21
18
17
16
15
14
13
12
+5V
2.5V
602k
120k
MAX872
BUF OUT
INT OUT
INT IN
4.7nF
100k
40.2k
MAX132
P0
P1
P2
P3
OSC1
6
AGND
IN LO
IN HI
V-
DGND
OSC2
5
15pF
512mV INPUT
-5V
32,768Hz
15pF
Figure 1. Test and Typical Application Circuit
_______________________________________________________________________________________
5
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