LMC6762

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SNOS739D – JULY 1997 – REVISED MARCH 2013

A voltage divider of R4 and R5 establishes a reference voltage V1 at the non-inverting input. By making the series

resistance of R1 and R2 equal to R5, the comparator will switch when VIN = 0. Diode D1 insures that V3 never

drops below

−0.7V. The voltage divider of R2 and R3 then prevents V2 from going below ground. A small amount

of hysteresis is setup to ensure rapid output voltage transitions.

Oscillator

Figure 33. Square Wave Generator

Figure 33 shows the application of the LMC6762 in a square wave generator circuit. The total hysteresis of the

loop is set by R1, R2 and R3. R4 and R5 provide separate charge and discharge paths for the capacitor C. The

charge path is set through R4 and D1. So, the pulse width t1 is determined by the RC time constant of R4 and C.

Similarly, the discharge path for the capacitor is set by R5 and D2. Thus, the time t2 between the pulses can be

changed by varying R5, and the pulse width can be altered by R4. The frequency of the output can be changed

by varying both R4 and R5.

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