NJU9214

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 - 7 ) Frequency ( f ) 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 - 8 ) RPM 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 - 9 ) Capacitance ( C ) 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.

( 1 - 10 ) Adapter ( ADP ) measurement

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.

( 2 ) Switch input Mode

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Both of lock and push type application have the chattering protective function which reject the chattering less

than 20ms.