FS9952_LP2

Resistance Measurement

R23 10M

R22 1.111M

R21 101.01k

R20 10k

R19 1k

R18 100k

R15 10k

Rx

J8

J6

Ohm

COM

15 TENM

14 ONEM

13 HUNK

12 TENK

11 ONEK

10 RL

6 SGND

FS9952

AGND

PTC

1.5k

9 CRES1

C11

27nF

R17 900k

8 SMV

Diagram 28 Resistance Measurement

Resistance measurement refers to standard resistance, and then takes a comparison between measuring

resistance and standard resistance to get the measuring resistance value. The standard resistance of 20MΩ

mode is 10MΩ (R23). The standard resistance of other modes are R23 to parallel respectively with R22, R21,

R20 and R19 to get 1MΩ, 100kΩ, 10kΩ, 1kΩ resistance. When doing resistance measurement, internal IC will

generate 0.4V voltage (relative to AGND), the voltage is output respectively to measuring resistance to

compare through resistance R23, R22, R21, R20 and R19. R18 connects to RL, which is the negative input of

the voltage reference that is gotten by the standard resistance. J3 and J5 are mode switches. When doing

resistance measurement, J6 and J8 are close. C11 is the wave filter capacitance of measuring point in

resistance measurement.

Diode Test

15 TENM

11 ONEK

8 SMV

7 DT

6 SGND

FS9952

J8

J6

VD

Diode

COM

PTC

1.5k

R23

10M

R19

1k

R17

900k

R16

100k

R15

10k

Diagram 29 Diode Measurement

Diode test generates 1.5V voltage from internal IC and outputs it through R19, then adds it to the positive of

diode through PTC. The positive voltage reduction VD generated by diode is approx. 0.5V-0.7V. VD is divided

by R17 and R16 to be 1/10 VD, then is amplified 10 times by internal OP and is delivered to A/D before

displaying the VD value. J6 and J8 are mode switches. When doing diode measurement, J6 and J8 are close.

Rev. 1.2

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