FS9922-DMM4

Rev. 1.4

21/37

AC Rectification Circuit

Diagram 18 is the average value rectification circuitry of FS9922-DMM4. In the circuit, AC signals enter IC

through R31, and then in the process of voltage division through R31, R30, R29, R28 and R27. The divided AC

signals come out from OP1O pin and enter IC through ADIP pin and ADIN pin after rectification. VR2 can adjust

the signal size to be the calibration of AC measurement.

Diagram 19 is the peak value rectification circuitry. Diagrams 20 and 21 are the true valid value rectification

circuitry. Users may determine which rectification circuit to select according to their needs.

+

_

+

_

+

_

C8

4.7uF

C10

0.47uF

C9

0.47uF

D3

D2

C12

27nF

C11

27nF

ToDigit Part

INL

INH

ToADC V-

ToADC V+

ADIP ADIN OP2O

OP2N

OP1O

OP1N

ToADC V+

FS9922-DMM4

OP2P

R13

100k

R12

100k

R11 22k

R10

22k

VR2

2k

R9

18k

R8

90k

R7

10k

Diagram 18: Average Rectification Circuit