© 2002 Microchip Technology Inc.

DS21461B-page 7

TC7136/TC7136A

2.0

PIN DESCRIPTIONS

Thedescriptionsof the pins arelistedinTable2-1.

TABLE 2-1:

PIN DESCRIPTION

Pin Number

(40-Pin PDIP)

Normal

(Reverse)

Symbol

Description

1

(40)

V+

Positive supply voltage.

2(39)

Activates the D section of the units display.

3(38)

Activates the C section of the units display.

4(37)

Activates the B section of the units display.

5(36)

Activates the A section of the units display.

6(35)

Activates the F section of the units display.

7(34)

Activates the G section of the units display.

8(33)

Activates the E section of the units display.

9(32)

Activates the D section of the tens display.

10

(31)

Activates the C section of the tens display.

11

(30)

Activates the B section of the tens display.

12

(29)

Activates the A section of the tens display.

13

(28)

Activates the F section of the tens display.

14

(27)

Activates the E section of the tens display.

15

(26)

Activates the D section of the hundreds display.

16

(25)

Activates the B section of the hundreds display.

17

(24)

Activates the F section of the hundreds display.

18

(23)

Activates the E section of the hundreds display.

19

(22)

Activates both halves of the 1 in the thousands display.

20

(21)

POL

Activates the negative polarity display.

21

(20)

BP

Backplane drive output.

22

(19)

Activates the G section of the hundreds display.

23

(18)

Activates the A section of the hundreds display.

24

(17)

Activates the C section of the hundreds display.

25

(16)

Activates the G section of the tens display.

26

(15)

V-

Negative power supply voltage.

27

(14)

The integrating capacitor should be selected to give the maximum voltage swing

that ensures component tolerance buildup will not allow the integrator output to sat-

urate. When analog common is used as a reference and the conversion rate is 3

readings per second, a 0.047

µF capacitor may be used. The capacitor must have a

low dielectric constant to prevent rollover errors. See Section 6.3, Integrating

Capacitor for additional details.

28

(13)

Integration resistor connection. Use a 180k

Ω for a 20mV full scale range and a

1.8M

Ω for 2V full scale range.

29

(12)

The size of the auto-zero capacitor influences the system noise. Use a 0.47

µF

capacitor for a 200mV full scale and a 0.1

µF capacitor for a 2V full scale.

See Section 6.1, Auto-Zero Capacitor for more details.

30

(11)

The low input signal is connected to this pin.

31

(10)

The high input signal is connected to this pin.

32

(9)

ANALOG

COMMON

This pin is primarily used to set the Analog Common mode voltage for battery

operation, or in systems where the input signal is referenced to the power supply.

See Section 7.3, Analog Common for more details. It also acts as a reference

voltage source.

33

(8)