DPP adds versatility to VFC

Posted on Mar 24, 2013

The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN, to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator`s output voltage. Feedback around both circuits provides the condition for oscillation. The DPP (digitally programmable potentiometer) in Figure 2 adds programmable limits to the Schmitt trigger and adds two powerful features to the VFC.

DPP adds versatility to VFC
Click here to download the full size of the above Circuit.
DPP adds versatility to VFC - image 1
Click here to download the full size of the above Image.

 the practical range of frequencies is 500 Hz to 25 kHz. Higher bandwidth, rail-to-rail CMOS versions of IC1 and IC2, and a greater R1/R2 ratio can extend the accuracy and range of the circuit. The automated, accurate setting of the scale factor saves manufacturing test time and eliminates the need for expensive, accurate...

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