FS9952_LP2

Voltage Measurement

VR2

10k

V

COM

R7

40k

R23 10M

R22 1.111M

R21 101.01k

R20 10k

R19 1k

R4

20k

PTC

1.5k

R14 10k

57 REFI

58 REFO

15 TENM

14 ONEM

13 HUNK

12 TENK

11 ONEK

V

Diagram 25 Voltage Measurement

When doing the voltage measurement, the measuring voltage is input from resistance R23 and DCmV is not

divided but enter IC directly; the voltages of 2V, 20V, 200V, 1000V modes are divided by R22, R21, R20, R19

and R23 to gain 1/10, 1/100, 1/1000, 1/10000 input voltages, then enter IC. To adjust the resistance value of

VR2 can do the calibration of the measurement.

The voltage division diagram of voltage measurement is as below:

Vout=0.1V

Vout=0.1V

Vout=0.1V

Vout=0.1V

Vin=1V

Vin=10V

Vin=100V

Vin=1000V

R23

10M

R23

10M

R23

10M

R23

10M

R22

1.111M

R21

101.01k

R20

10k

R19

1k

Diagram 26 Voltage Division Circuit Diagram

The formula of voltage division is:

VO=Vin × [Rx/（R23+Rx）]

Rx is R22, R21, R20 or R19

Therefore, the accuracy of R19, R20, R21, R22 and R23 decide the accuracy of the measurement.

AcmV voltage enters IC through R23 and is divided by R22 and R23 to get 1/10 voltage, then is amplified

10 times to fulfill the measurement by A/D, so the accuracy of R5 and R8 is also determine the measuring

accuracy of AcmV voltage.

Current Measurement

Rev. 1.2

27/34