NJM4151(2003) View Datasheet(PDF) - Japan Radio Corporation

Part Name

Description

Manufacturer

NJM4151
(Rev.:2003)

V-F / F-V CONVERTOR

Japan Radio Corporation  

NJM4151

Figure 3. Precision Voltage-to-Frequency Converter Single Supply

3. Precision Voltage-to-Frequency Converter

In this application (Figure 4) the NJM4151 VFC is used with an operational amplifier integrator to provide typical

linearity of 0.05％ over the range of 0 to -10V. Offset is adjustable to zero. Unlike many VFC designs which lose linearity

below 10mV, this circuit retains linearity over the full range of input voltage, all the way to 0V.

Trim the full scale adjust pot at VI = -10V for an output frequency of 10kHz. The offset adjust pot should be set for

10Hz with an input voltage of -10mV.

The operational amplifier integrator improves linearity of this circuit over that of Figure 2 by holding the output of the

source, Pin 1, at a constant 0V. Therefore linearity error due to the current source output conductance is eliminated. The

diode connected around the op-amp prevents the voltage at NJM4151 pin 7 from going below 0. Use a low-leakage

diode here, since any leakage will degrade the accuracy. This circuit can be operated from a single positive supply if an

NJM3403A ground-sensing op-amp is used for the integrator. In this case, the diode can be left out. Note that even

though the circuit itself will operate from a single supply, the input voltage is necessarily negative. For operation above

10kHz, bypass NJM4151 pin 6 with 0.01µF.

Figure 4. Precision Voltage-to-Frequency Converter

Ver.2003-12-09

-5-

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