Data Sheet

AD737

Rev. J | Page 17 of 24

COM

+V

AD589

1.23V

CAV

CC

POWER

DOWN

0.1µF

CC

10µF

SWITCH CLOSED

ACTIVATES

POWER-DOWN

MODE. AD737 DRAWS

JUST 40µA IN THIS MODE

2V

20V

200V

9MΩ

900kΩ

90kΩ

10kΩ

VIN

200mV

VIN

–VS

+

+

+VS

+

1µF

OUTPUT

1MΩ

–VS

+VS

1N4148

1N4148

47kΩ

1W

1µF

+

COMMON

33µF

REF LOW

REF HIGH

31/2 DIGIT ICL7136

TYPE CONVERTER

LOW

HIGH

ANALOG

9V

200kΩ

20kΩ

50kΩ

+

1PRV

0.01µF

RMS

CORE

AD737

BIAS

SECTION

INPUT

AMPLIFIER

8kΩ

8kΩ

1

2

3

4

8

7

6

5

FULL-WAVE

RECTIFIER

Figure 27. 3½ Digit DVM Circuit

COM

INPUT

CAV

CAV

33µF

CF

0.47µF

C1

0.47µF

C5

1µF

C4

2.2µF

R7

100kΩ

R4

5kΩ

R2

5kΩ

R3

78.7kΩ

R5

80.6kΩ

R1

69.8kΩ

1%

R8

100kΩ

C3

0.01µF

0.01µF

C2

0.01µF

CC

POWER

DOWN

INPUT SCALE FACTOR ADJ

VIN

–VS

OUTPUT

+VS

+

OUTPUT

AD737

+

5V

5V

2.5V

AD8541AR

5V

NC

NC = NO CONNECT

OUTPUT ZERO

ADJUST

1

2

3

4

8

7

6

5

1

4

7

5

3

6

2

Figure 28. Battery-Powered Operation for 200 mV Maximum RMS Full-Scale Input

VOUT

RMS

CORE

CC

VIN

CF

10µF

COM

OUTPUT

AD737

BIAS

SECTION

INPUT

AMPLIFIER

SCALE FACTOR

ADJUST

8kΩ

8kΩ

POWER

DOWN

–VS

+VS

+

CAV

1

2

3

4

8

7

6

5

100Ω

200Ω

CAV

33µF

CC

10µF

+

+

FULL-WAVE

RECTIFIER

Figure 29. External Scale Factor Trim