LMC6772

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SNOS749F – SEPTEMBER 1995 – REVISED MARCH 2013

OUTPUT SHORT CIRCUIT CURRENT

The LMC6772 has short circuit protection of 40 mA. However, it is not designed to withstand continuous short

circuits, transient voltage or current spikes, or shorts to any voltage beyond the supplies. A resistor is series with

the output should reduce the effect of shorts. For outputs which send signals off PC boards additional protection

devices, such as diodes to the supply rails, and varistors may be used.

HYSTERESIS

If the input signal is very noisy, the comparator output might trip several times as the input signal repeatedly

passes through the threshold. This problem can be addressed by making use of hysteresis as shown below.

Figure 31. Canceling the Effect of Input Capacitance

The capacitor added across the feedback resistor increases the switching speed and provides more short term

hysteresis. This can result in greater noise immunity for the circuit.

SPICE MACROMODEL

A Spice Macromodel is available for the LMC6772. The model includes a simulation of:

•

Input common-mode voltage range

•

Quiescent and dynamic supply current

•

Input overdrive characteristics

and many more characteristics as listed on the macromodel disk.

A SPICE macromodel of this and many other op amps is available at no charge from the WEBENCH Design

Center Team at www.ti.com

Copyright © 1995–2013, Texas Instruments Incorporated

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