MAXIM MAX132 User Manual

19-0009; Rev 2; 8/95

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

±18-Bit ADC with Serial Interface

_______________General Description

The MAX132 is a CMOS, 18-bit plus sign, serial-output,
analog-to-digital converter (ADC). Multi-slope integra­tion 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 mea­surements. Typical supply current is only 60µA and is
reduced to 1µA in sleep mode. Four serially pro­grammed 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 extend­ed temperature grades.

High resolution, compact size, and low power make this
device ideal for data loggers, weigh scales, data-acqui­sition systems, and panel meters.

________________________Applications

Remote Data Acquisition
Battery-Powered Instruments
Industrial Process Control
Transducer-Signal Measurement

Pressure, Flow, Temperature, Voltage
Current, Resistance, Weight

____________________________Features

♦ Low Supply Current:

60µA (Normal Operation)
1µA (Sleep-Mode Operation)

♦ ±0.006% FSR Accuracy at 16 Conv/sec
♦ Low Noise: 15µV

RMS

♦ Serial I/O Interface with Programmed Output for

Mux and PGA

♦ Performs up to 100 Conv/sec
♦ ±2pA Input Current
♦ 50Hz/60Hz Rejection

______________Ordering Information

PART

MAX132CNG
MAX132CWG
MAX132C/D 0°C to +70°C
MAX132ENG
MAX132EWG
MAX132MRG -55°C to +125°C

* Contact factory for dice specifications.
** Contact factory for availability and processing to MIL-STD-883.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C
0°C to +70°C

-40°C to +85°C 24 Narrow Plastic DIP

-40°C to +85°C

24 Narrow Plastic DIP
24 Wide SO
Dice*

24 Wide SO
24 Narrow CERDIP**

MAX132

________________Functional Diagram

CREF- CREF+

CS
SCLK
EOC
DIN
DOUT

MAX132

P0
P1
P2
P3

________________________________________________________________

V+

BUF OUT

INT OUT

INT IN

REF+

REF-

AGND

IN LO

IN HI

V-

DGND

OSC2OSC1

+5V

602k

4.7nF

±512mV INPUT

-5V

__________________Pin Configuration

TOP VIEW

CS

1

DIN

2

DOUT

3

SCLK

4

OSC2
OSC1

P0
P1

P2
P3

EOC

DGND

MAX132

5
6
7
8

9
10
11
12

DIP/SO

Maxim Integrated Products

Call toll free 1-800-998-8800 for free samples or literature.

24
23
22
21
20
19
18
17
16
15
14
13

V+
BUF OUT
INT OUT
INT IN
CREF­CREF+
REF+
REF­AGND
IN LO
IN HI
V-

1

±18-Bit ADC with Serial Interface

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

MAX132

Narrow Plastic DIP (derate 8.70mW/°C above +70°C)....478mW

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
f

= 32,768Hz, 60Hz mode, TA= T

CLK

ACCURACY

Zero Error

Rollover Error
Conversion Time

Input Voltage Range
Leakage Current IN HI, IN LO

Common-Mode Rejection Ratio IN HI = IN LO
Common-Mode Range

Zero-Reading Drift

POWER REQUIREMENTS

Negative Supply Voltage
Positive Supply Rejection

Negative Supply Rejection

Negative Supply Current

Positive Sleep-Mode Current

Digital Ground Sleep-Mode
Current

to T

MIN

(Note 1)
VINHI = 0V % of FSR
(Notes 2, 3)
(Note 4)
f

= 32.768Hz

CLK

IN HI to IN LO, for specified accuracy

IN HI = IN LO V±3.0

(Note 3) ppm/°C±0.15 ±1.5
(Note 3) ppm/°C±5Scale Factor Temp. Coefficient

VINHI = 400mV, V- = -5.0V,

4.5V ≤ V+ ≤ 5.5V
VINHI = 400mV, V- = 5.0V,

-5.5V ≤ V- ≤ -4.5V
Digital input = 0V or V+

Digital input = 0V or V+
Digital input = 0V or V+
Digital input = 0V or V+
Digital input = 0V or V+ µA-1 -10Negative Sleep-Mode Current

Digital input = 0V or V+ µA0±2

, unless otherwise noted.)

MAX

CONDITIONS

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

TA= +25°C
TA= T
TA= +25°C
TA= +25°C
TA= T

TA= T

VCM= ±3.0V

TA= +25°C

TA= +25°C
TA= T
TA= +25°C
TA= T

MIN

MIN

MIN

MIN

MIN

to T

to T

to T

to T

to T

INT

MAX

MAX

MAX

MAX

MAX

= 602kΩ, C

= 0.0047µF, C

INT

±18Resolution

0 ±0.0076

±0.0168

0 ±0.010

±0.032

±2 ±10TA= +25°C

±12 ±250

±0.009 ±0.032VCM= ±500mV

±0.25 ±0.50

±0.003 ±0.0061
±0.003 ±0.0168
±0.003 ±0.0061
±0.003 ±0.0168

REF

% of FSR±0.0015 ±0.006Integral Nonlinearity
% of FSR

% of FSR

% of FSR±3.1Read-Zero 50Hz/60Hz Range

% of FSR

% of FSR

= 0.1µF,

UNITSMIN TYP MAXPARAMETER

Bits

ms63
mV±512

pA

µV15RMS Noise

V4.5 5.5Positive Supply Voltage
V-5.5 -4.5

µA60 125Positive Supply Current
µA-35 -65
µA-25 -60Digital Ground Supply Current
µA110

2 _______________________________________________________________________________________

±18-Bit ADC with Serial Interface

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, R
f

= 32,768Hz, 60Hz mode, TA= T

CLK

MIN

to T

, unless otherwise noted.)

MAX

CONDITIONS

DIGITAL SECTION

Output High

Output Low
Input High

Input Low
Input Current
Input Capacitance

DOUT, I

OH

DOUT, I

V

EOC, P0–P3, I

V

DOUT, I

OL

EOC, P0–P3, I
Referred to DGND, 4.5V ≤ V+ ≤ 5.5V, CS, DIN, SCLK

IH

Referred to DGND, 4.5V ≤ V+ ≤ 5.5V, CS, DIN, SCLK

IL

CS, DIN, SCLK, and DOUT when three-stated

IN

CS, DIN, SCLK, and DOUT when three-stated

IN

OUT
OUT

OUT

= -1mA
= -100µA

= -100µA

OUT

= 1.6mA

= 100µA

OUT

= 602kΩ, C

INT

= 0.0047µF, C

INT

3.5 4.3

4.0 4.5

4.0 4.7

0.1 0.4

0.1 0.4

INTERFACE TIMING

(Test Circuit of Figure 1, Figure 2, V+ = 5V, V- = -5V, DGND = AGND = 0V, TA= +25°C, unless otherwise noted.) (Note 3)

CONDITIONS

CS Lead Time
CS Lag Time
S

High Time

CLK

S

Low Time

CLK

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

1
2
3
4
5
6
7
8

9
10
11
12

See Figure 3

See Figure 4

REF

MAX132

= 0.1µF,

UNITSMIN TYP MAXSYMBOLPARAMETER

V

V
V2.4V

V0.8V
nA±10 ±500I
pF5C

UNITSMIN TYP MAXSYMBOLPARAMETER

ns500t
ns400t
ns400t
ns300t
µs1t
ns0t
ns200t
ns320t
ns60t
ns320t
ns230 350t
ns230 350t

Note 1: ±18-bit accuracy achieved by averaging multiple conversions.
Note 2: Maximum deviation from best straight-line fit.
Note 3: Guaranteed by design, not tested.
Note 4: Difference in reading for equal positive and negative inputs near full scale.

_______________________________________________________________________________________ 3

±18-Bit ADC with Serial Interface

__________________________________________Typical Operating Characteristics

ERROR vs. COMMON-MODE

INPUT VOLTAGE (V

0.05
IN HI = IN LO

0

-0.05

MAX132

-0.10

-0.15

ERROR (% OF FSR)

-0.20

-0.25

-0.30

-3 -2 -1 0 1 2 3 4-4
COMMON-MODE VOLTAGE (V)

vs. CRYSTAL FREQUENCY

140
120
100

80
60
40
20

SUPPLY CURRENT (µA)

0

-20

-40
0 50 150

100 200 250 300 350

CRYSTAL FREQUENCY (kHz)

LO–AGND)

IN



SUPPLY CURRENT

50Hz/60Hz READ-ZERO OFFSET

vs. VREF

4.5

MAX132-01

4.0

3.5

3.0

2.5

2.0

1.5

1.0

READ-ZERO OFFSET (% OF FSR)

0.5
0

50Hz MODE

0 0.5 1.5

60Hz MODE

1.0 2.0

VREF (V)

MAX132-02

READ-ZERO OFFSET (% OF FSR)

FULL-SCALE ROLLOVER ERROR

vs. VREF

0.10

V+

V-

MAX132-04

0.08

0.06

0.04

0.02

ROLLOVER ERROR (% OF FSA)

0

0 0.5 1.0 1.5 2.52.0

VREF (V)

MAX132-05

)

RMS

NOISE (µV

50Hz/60Hz READ-ZERO OFFSET

vs. TEMPERATURE

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2
0

-40 -20 20

60Hz MODE, VREF = 545mV

50Hz MODE, VREF = 655mV

0 40 60 80 100

TEMPERATURE (°C)

NOISE vs. NUMBER

OF SAMPLES AVERAGED

20

15

10

5

0

0102030 5040

NUMBER OF SAMPLES AVERAGED

MAX132-03

MAX132-06

______________________________________________________________Pin Description

PIN

CHIP SELECT Input has 3 functions: 1) When low, selects IC for communication; 2) on rising edge, loads

CS1

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.DIN2
Serial Data Out, D7 first bit out. Data is clocked out at the falling edge of SCLK. High impedance when CSis high.DOUT3

SCLK4

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.OSC25
Oscillator Input 1 is normally connected to a 32,768Hz crystal, or may be connected to an external clock.OSC16
User-programmable output bit 0—programmed through the serial port.P07
User-programmable output bit 1—programmed through the serial port.P18

4 _______________________________________________________________________________________

FUNCTIONNAME

±18-Bit ADC with Serial Interface

_________________________________________________Pin Description (continued)

PIN

User-programmable output bit 2—programmed through the serial port.P29
User-programmable output bit 3—programmed through the serial port.P310
End of Conversion Output goes high at end of conversion.EOC11
Digital Ground—power-supply returnDGND12
Negative Supply, nominally -5VV-13
Positive Analog InputIN HI14
Negative Analog InputIN LO15
Analog GroundAGND16
Negative Reference InputREF-17
Positive Reference InputREF+18
Positive Reference Capacitor connectionCREF+19
Negative Reference Capacitor connectionCREF-20
Integrator Input. Connect the integration capacitor between INT IN and INT OUT.INT IN21
Integrator Output. To minimize noise, this pin should drive the capacitor’s outside foil (negative end).INT OUT22
Buffer-Amplifier Output drives the integrator resistor.BUF OUT23
Positive Supply, nominally +5VV+24

FUNCTIONNAME

MAX132

1

CS

4

SCLK

11

EOC

2

DIN

3

DOUT

7

P0

8

P1

9

P2

10

P3

32,768Hz

15pF

Figure 1. Test and Typical Application Circuit

REF+

REF-

IN LO

IN HI

15pF

+5V

24

V+

602k

23
22

4.7nF

21
18

17
16
15
14
13

V-

-5V

12

0.1µF

20

CREF- CREF+

MAX132

65

19

BUF OUT

INT OUT

INT IN

AGND

DGND

OSC2OSC1

120k

100k

40.2k

512mV INPUT

2.5V

MAX872

_______________________________________________________________________________________ 5