ICL7135 datasheet(13/15 Pages) INTERSIL

13 / 15 page

FN3093.3

Typical Integrator Amplifier Output Waveform (INT Pin)

Design Information Summary Sheet

• CLOCK INPUT

The ICL7135 does not have an internal oscillator. It

requires an external clock.

fCLOCK (Typ) = 120kHz

• CLOCK PERIOD

tCLOCK = 1/fCLOCK

• INTEGRATION PERIOD

tINT = 10,000 x tCLOCK

• 60/50Hz REJECTION CRITERION

tINT/t60Hz or tINT/t50Hz = Integer

• OPTIMUM INTEGRATION CURRENT

IINT = 20µA

• FULL-SCALE ANALOG INPUT VOLTAGE

VlNFS (Typ) = 200mV or 2V

• INTEGRATE RESISTOR

• INTEGRATE CAPACITOR

• INTEGRATOR OUTPUT VOLTAGE SWING

•VINT MAXIMUM SWING:

(V- + 0.5) < VINT < (V+ - 0.5V)

VINT Typically = 2.7V

• DISPLAY COUNT

• CONVERSION CYCLE

tCYC = tCL0CK x 40002

when fCLOCK = 120kHz, tCYC = 333ms

• COMMON MODE INPUT VOLTAGE

(V- + 1V) < VlN < (V+ - 0.5V)

• AUTO-ZERO CAPACITOR

0.01

µF < C

AZ < 1µF

• REFERENCE CAPACITOR

0.1

µF < CREF < 1µF

• POWER SUPPLY: DUAL

±5V

V+ = +5V to GND

V- = -5V to GND

• OUTPUT TYPE

4 BCD Nibbles with Polarity and Overrange Bits

There is no internal reference available on the ICL7135. An

external reference is required due to the ICL7135’s 41/2

digit resolution.

INT

INFS

INT

-----------------

INT

() I

INT

()

INT

--------------------------------

INT

() I

INT

()

INT

--------------------------------

COUNT

10 000

REF

-----------------

AUTO ZERO PHASE

(COUNTS)

30001 - 10001

INTEGRATE

PHASE FIXED

10000 COUNTS

DE-INTEGRATE PHASE

1 - 20001 COUNTS

TOTAL CONVERSION TIME = 40002 x tCLOCK

ICL7135

ICL7135 Datasheet(PDF) 13 Page - Intersil Corporation

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