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
(1-7) Frequency ( f ) measurement
The input voltage is divided by the attenuator, and then the attenuator output is supplied to counter through the
buffer.
The divided voltage is converted to DC voltage by the external RMS/DC converter, and the dividing voltage
ratio of the input attenuator is changed by this DC voltage, Noises or distorted waveforms sometimes show
different display against actual frequency.
The frequency range is always fixed to the Auto-range mode. It is able to switch from 100Hz to 1,000kHz and
the measurement cycle is 1 time a second.
(1-8) RPM measurement
It is possible to measure numbers of revolution like as the revolutions of engine. The measurement is same
way as the frequency measurement. The revolutions are calculated by the value of 60 times the frequency.
The revolution range is always selected one of 6,000 to 600krpm automatically.
The minimum input voltage ( wave amplitude ) is about 300mV and the measurement cycle is 1 time a
second.
(1-9) Capacitance ( C ) measurement
The constant-current charges the measured capacitor, and the charging time, while the voltage of
capacitance reaches to the reference voltage, is measured and converted to the capacitance value.
If the measured capacitor has any electric charges, accurate measurement is not available. Therefore the
measured capacitor must be discharged before measurement.
The sense terminal is the OVX terminal.
(1-10) Adapter ( ADP ) measurement
The voltage between the ADP terminal and the SGND is supplied to the A/D converter directly. Both of ADP
terminal ( + ) and SGND terminal ( – ) are High-impedance in DC400mV range.
Therefore, it is also used as differential input.
(2) Switch input Mode
The lock or push type input switch is applied for function selection. The switch type is selected in both of auto
and manual ranges by the RMS terminal setting.
When the push type switch is selected, auto ranging is always selected.
When the lock type switch is selected and the RMS terminal is GND ( L ) level, all ranges are selected by
switches. But if the RMS terminal is VDD level ( H ), auto range, manual range selection and the range set are
performed by a push type switch.
KMS Terminal
H
H
L
RMS Terminal
H
L
∗
SWITCH
Lock type
Push type
RANGE
Full Auto
Manual
Full Auto
∗ : ( Don't Care )
Both of lock and push type application have the chattering protective function which reject the chattering less
than 20ms.
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