5

24

OSC SEL

Oscillator Select - Input high configures OSC IN, OSC OUT, BUF OSC OUT as RC oscillator - clock

will be same phase and duty cycle as BUF OSC OUT.

Input low configures OSC IN, OSC OUT for crystal oscillator - clock frequency will be 1/58 of

frequency at BUF OSC OUT.

25

BUF OSC OUT

Buffered Oscillator Output

26

RUN/HOLD

Input High - Conversions continuously performed every 8192 clock pulses.

Input Low - Conversion in progress completed, converter will stop in Auto-Zero 7 counts before

integrate.

27

SEND

Input - Used in handshake mode to indicate ability of an external device to accept data. Connect to

+5V if not used.

28

V-

Analog Negative Supply - Nominally -5V with respect to GND (Pin 1).

29

REF OUT

Reference Voltage Output - Nominally 2.8V down from V+ (Pin 40).

30

BUFFER

Buffer Amplifier Output.

31

AUTO-ZERO

32

INTEGRATOR

33

COMMON

Analog Common - System is Auto-Zeroed to COMMON.

34

INPUT LO

Differential Input Low Side.

35

INPUT HI

Differential Input High Side.

36

REF IN +

Differential Reference Input Positive.

37

REF CAP +

Reference Capacitor Positive.

38

REF CAP-

Reference Capacitor Negative.

39

REF IN-

Differential Reference Input Negative.

40

V+

Positive Supply Voltage - Nominally +5V with respect to GND (Pin 1).

NOTE: All digital levels are positive true.

PIN

SYMBOL

DESCRIPTION

ICL7109