BETALM2907-NFrequency-to-voltage converter
Turn changing speed into a measurable voltage.
LM2907-N converts the rate of an alternating input into an analog voltage. Its input comparator, charge pump and output amplifier form a compact tachometer interface for a magnetic pickup or a suitable test signal. Each complete input cycle transfers a nominal charge of C1 × VCC into the output filter. R1 converts the average current to voltage, while C2 reduces ripple and sets how quickly the reading settles. This reference selects the eight-pin LM2907N-8 and LM2907M-8 packages. Their input must cross ground, and their amplifier positive input is internally joined to the pump output. Fourteen-pin versions have a different pin map; the related LM2917 additionally includes a Zener regulator.
