3-220

TELCOM SEMICONDUCTOR, INC.

3-1/2 DIGIT

ANALOG-TO-DIGITAL CONVERTERS

TC7126

TC7126A

PIN DESCRIPTION

40-Pin PDIP

Pin Number

Normal

(Reverse)

Name

Description

1

(40)

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)

Negative power supply voltage.

27

(14)

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

that ensures component tolerance build-up will not allow the integrator output to

saturate. 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 roll-over errors. See "Integrating Capaci-

tor" section for additional details.

28

(13)

Integration resistor connection. Use a 180 k

Ω resistor for a 200 mV full-scale

range and a 1.8 M

Ω resistor for a 2V full-scale range.

29

(12)

The size of the auto-zero capacitor influences system noise. Use a 0.33

µF

capacitor for 200 mV full scale, and a 0.033

µF capacitor for 2V full scale. See

paragraph on 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

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 paragraph on analog common for more details. It also acts as a reference

voltage source.

33

(8)

–

See pin 34.

COMMON