AN795 Datasheet, PDF (1/15 Pages) Microchip Technology – Voltage-to-Frequency/Frequency-to-Voltage Converter

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.
V_{1 TC9400}
V/F
V_{2 TC9400}
V/F
÷N
One
Shot
Output = N
V₁
V₂
Latch
Counter
One
Shot
Reset
Latch
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. Optical and magnetic sensors will convert these flows and revolutions into a digital signal which, in turn, can be converted to a
proportional voltage by the use of a frequency-to-voltage (F/V) converter. A simple voltmeter will then give a visual indication of the
speed.
Analog Display
Speed
Sensor
TC9400
F/V
(Optical or Magnetic)
FIGURE 2: RPM/speed indicator.
RPM
DVM Display
RPM
© 2002 Microchip Technology, Inc.
DS00795A-page 1