3-135

TELCOM SEMICONDUCTOR, INC.

7

6

5

4

3

1

2

8

3-1/2 DIGIT A/D CONVERTERS

TC14433

TC14433A

Figure 14. 3-1/2 Digit Voltmeter with Low Component Count Using Common Cathode Displays

X

CLK1

CLK0

OR

Q

Q

TC14433

INPUT

V

X

300k

RESISTOR

NETWORK

OR

INDIVIDUAL

RESISTOR*

R

+5V

MINUS

CONTROL

+5V

R

COMMON

CATHODE

LED DISPLAY

75492

OR

1413*

DIGIT DRIVERS

V

(MINUS)

EE**

ALTERNATE OVERRANGE CIRCUIT

WITH SEPARATED LED

+5V

OR

1/6

1/7

1413

75492

OR

B1

A

B

C

D

LT

a

b

c

d

e

f

g

I4511B

R /C

CC0 C0

For V

= 2000V

V : 1.999V full scale

For V

= 200 mV

V : 199.9 mV full scale

(change 470k to R = 27k

and decimal point position)

*To increase segment current

capability add two 75491 ICs

between 14511B and Resistor

Network. The use of the 1413

as digit driver increases digit

current capability over the 75492.

Peak digit current for an eight

displayed is 7 times the segment

current.

**V can range between –2.8 and

–11V.

470k 0.1

µF 0.1µF

DS DS DS DS

AG

V

V

DU

R

EOC

REF

V

REF

REF

11

1

1

2

0

1

43

2

1

M

1

LE

+5V

100k

Ω

TC04

27k

Ω