ICL7216

FN3084 Rev.5.00

Page 13 of 15

Oct 25, 2004

FIGURE 17. CIRCUIT FOR DEVELOPING UNDERRANGE AND OVERRANGE SIGNAL FROM ICL7126 OUTPUTS

FIGURE 18. AC TO DC CONVERTER WITH ICL7126

13

1

2

3

4

5

6

7

8

9

10

11

12

14

15

16

17

18

19

20

V+

D1

C1

B1

A1

F1

G1

E1

D2

C2

B2

A2

F2

E2

D3

B3

F3

E3

AB4

POL

28

40

39

38

37

36

35

34

33

32

31

30

29

27

26

25

24

23

22

21

OSC 1

OSC 2

OSC 3

TEST

REF HI

REF LO

COMMON

IN HI

IN LO

A-Z

BUFF

INT

V-

G2

C3

A3

G3

BP

O /RANGE

U /RANGE

CD4023 OR

74C10

CD4077

TO LOGIC

V+

TO

LOGIC

V-

GND

28

40

39

38

37

36

35

34

33

32

31

30

29

27

26

25

24

23

22

21

OSC 1

OSC 2

OSC 3

TEST

REF HI

REF LO

COMMON

IN HI

IN LO

A-Z

BUFF

INT

V -

G2

C3

A3

G3

BP

50pF

TO PIN 1

0.1

F

180k



10k



220k



180k



0.047

F

0.22

F

TO BACKPLANE

TO DISPLAY

Test is used as a common-mode reference level to ensure compatibility with most op amps.

10

F

9V

10

F

470k



1

F

4.3k



100pF

(FOR OPTIMUM

BANDWIDTH)

1

F

10k



10k



1N914

1

F

0.22

F

5

F

ICL7611

2.2M



+

-

100k



AC IN

SCALE FACTOR ADJUST

750

