FS9721_LP1 datasheet(28/41 Pages) FORTUNE

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FS9721_LP1

Rev. 2.0

29/41

14.12

Voltage Measurement

VR2

10k

PTC

REFI

REFO

TENM

ONEM

HUNK

TENK

ONEK

SGND

FS9721_LP1

COM

R10 40k

R720k

R26

1.111M

R25 101.01k

R24

10k

R23 1k

R18 10k

R27 10M

Diagram 24

Voltage Measurement

When doing the voltage measurement, the measuring voltage is input from resistance R27, and

DCmV is not divided, but enter IC directly; 4V, 40V, 400V, 1000V mode is divided by R26, R25, R24,

R23 and R27 to gain 1/10, 1/100, 1/1000, 1/10000 voltage, then enter IC. To adjust the resistance

value of VR2 can do the calibration of measurement.

Voltage Division of Voltage Measurement Diagram is as below:

Vout=0.1V

Vin=1V

Vin=10V

Vin=100V

Vin=1000V

R27

10M

R27

10M

R27

10M

R27

10M

R26

1.111M

R25

101.01k

R24

10k

R23

Diagram 25

Voltage Division Circuit Diagram

The formula of voltage division is:

Vout=Vin × [Rs/ (R27+Rs )]

Rs is R26, R25, R24 or R23

Therefore, the accuracy of R23, R24, R25, R26 and R27 determine the accuracy of the

measurement.

AcmV enter IC through R27 and is divided by R26 and R27 to get 1/10 voltage, then is

amplified 10 times internal to fulfill the measurement, so the accuracy of R9 and R8 is also

determine the measuring accuracy of ACmV.

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