NJU9214 データシートの表示（PDF） - Japan Radio Corporation
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NJU9214 Datasheet PDF : 28 Pages
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NJU9214
(1-2) Resistance measurement ( Ω )
As shown below, six type resistors ( 10MΩ, 1MΩ, 100kΩ, 10kΩ, 1kΩ, 100Ω ) connecting VR2 to VR7 are
used for reference resistors of each range.
The output voltage on the measurement terminal is almost same as the voltage inputted Vref3.
As shown in Application circuits ( 1 ) to ( 3 ), an input protective diode must be connected with the OVH
terminal. In resistance measurement, continuity test, diode check and capacitance mode, if the NJU9214 is
supplied high voltage on the OVH terminal from the external, the NJU9214 may be broken completely.
In the R1 ( 400Ω ) range, sometimes the resistor value shows wrong display because of the influence by test
leads and wiring resistances of a circuit board. In this case, it needs to adjust on the relative function using the 0
Ω resistance.
In the R6 ( 40MΩ ) range, it may take a time to get the correct measurement value by the influence of
parasitic capacitance and may not show the stable value by the noise effects.
RANGE
R1 ( 400Ω )
R2 ( 4kΩ )
R3 ( 40kΩ )
R4 ( 400kΩ )
R5 ( 4000kΩ )
R6 ( 40kΩ )
Refer. Resistance Value
100Ω
1kΩ
10kΩ
100kΩ
1MΩ
10MΩ
(1-3) Continuity test(
)
The input attenuator is fixed to 400Ω range of the resistance measurement mode. When the value is less
than 40Ω, the buzzer sounds. The output voltage on the measurement terminal is about 0.4V.
If the display doesn't show 0Ω by resistances of lead wire when the terminals are shorted,
this case requires adjustment at 0Ω using the relative function.
(1-4) Diode check(
)
The input attenuator is fixed to DC4V range. The output voltage on the OVH terminal is about 5V ( VDDA ),
and it is supplied to the measurement terminal through the SW1 ( external switch or relay ).
(1-5) Current ( DCmA, ACmA ) measurement
Current measurement provides the Auto - Manual 2-range mode( RMS = H ) and the Manual 4-range mode
( RMS = L ). These are changed by status of the RMS terminal. Each mode needs its own application circuit.
In the Auto-manual 2-range mode, the sense terminal is IVSL terminal at the 40mA range and IVSH terminal
at the 400mA range.
In the Manual 4-range mode, the sense terminal is IVSL. In this mode, switching range is performed by
changing the reference resistors. The SW for the reference resistor change must be operated together with the
SWs connecting to ' RC1 to RC3 '. ( Refer to ( 2 - 1 - 3 ) )
(1-6) Current ( DCA, ACA ) measurement
It is fixed to the 40A range. The sense terminal is the IVSH terminal.
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