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AN795
Voltage-to-Frequency/Frequency-to-Voltage Converter
Author: Michael O. Paiva, Microchip Technology, Inc.
RATIOMETRIC MEASUREMENT (ANALOG DIVISION)
One of the most difficult circuits to build is one which will divide one analog signal by another. Two voltage-to-frequency (V/F) converters can do such division with ease. The numerator is counted directly as a signal, while the denominator forms the time base.
Latch V1 V2 TC9400 V/F TC9400 V/F ÷N One Shot Counter One Shot Reset Latch
V Output = N 1 V2
FIGURE 1: Ratiometric measurement (analog division).
RPM/SPEED INDICATOR
Flow rates and revolutions per second are nothing more than frequency signals, since they measure the number of events per time period.