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Frequency-to-voltage converter

LM2907-N Working Principle

Learn how LM2907-N works with an illustrated explanation and practical readings.

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LM2907-N at a glance

Follow the labeled connections and functional stages

LM2907-N working principle: illustrated functional stages, basic circuit and connections
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How it works

3 stages · Explore one step at a time

Step 1 / 3

Detect the zero crossings

The eight-pin input compares TACH+1 with GND8. Hysteresis rejects small changes close to the crossing.

Step 2 / 3

Transfer and average charge

C1 charges and discharges on alternate half cycles. Both pulses are mirrored into R1 and C2 at pin 3.

Step 3 / 3

Buffer the reading

Connecting EMIT4 to IN−7 makes the amplifier follow the filtered voltage, while COL5 supplies the output transistor.

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