TC835

DS21478B-page 6

© 2002 Microchip Technology Inc.

2.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1:

PIN FUNCTION TABLE

Pin Number

28-Pin PDIP

Symbol

Description

1

V-

Negative power supply input.

2

REF IN

External reference input.

3

ANALOG COMMON

Reference point for REF IN.

4

INT OUT

Integrator output. Integrator capacitor connection.

5

AZ IN

Auto zero input. Auto zero capacitor connection.

6

BUFF OUT

Analog input buffer output. Integrator resistor connection.

Reference capacitor input. Reference capacitor negative connection.

Reference capacitor input. Reference capacitor positive connection.

9

-INPUT

Analog input. Analog input negative connection.

10

+INPUT

Analog input. Analog input positive connection.

11

V+

Positive power supply input.

12

D5

Digit drive output. Most Significant Digit (MSD)

13

B1

Binary Coded Decimal (BCD) output. Least Significant Bit (LSB)

14

B2

BCD output.

15

B4

BCD output.

16

B8

BCD output. Most Significant Bit (MSB)

17

D4

Digit drive output.

18

D3

Digit drive output.

19

D2

Digit drive output.

20

D1

Digit drive output. Least Significant Digit (LSD)

21

BUSY

Busy output. At the beginning of the signal-integration phase, BUSY goes High and

remains High until the first clock pulse after the integrator zero crossing.

22

CLOCK IN

Clock input. Conversion clock connection.

23

POLARITY

Polarity output. A positive input is indicated by a logic High output. The polarity output is

valid at the beginning of the reference integrate phase and remains valid until determined

during the next conversion.

24

DGND

Digital logic reference input.

25

RUN/HOLD

Run / Hold input. When at a logic High, conversions are performed continuously. A logic

Low holds the current data as long as the Low condition exists.

26

STROBE

Strobe output. The STROBE output pulses low in the center of the digit drive outputs.

27

OVERRANGE

Over range output. A logic High indicates that the analog input exceeds the full scale input

range.

28

UNDERRANGE

Under range output. A logic High indicates that the analog input is less than 9% of the full

scale input range.