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LM397: Applicatioin

Nanfang Liao
Intellectual 2085 points
Part Number: LM397
Other Parts Discussed in Thread: LM339

Hello team,

My customer uses our LM397, there is  29V of BAT_F, but sometimes the VS voltage change from 12V to 0, the voltage of pin4 is higher than pin5, it is risk? our part will be broken? thanks

cid:image001.png@01D26A6A.F1351070

Regards,

Nanfang

Regards,

Nanfang

  • 0
    TI__Guru 62266 points
    Hello Nanfang,

    The LM397 is the single version of the LM339/393 comparator series.

    The LM339/393 series has the unique ability to tolerate input voltages above V+, even with no supply voltage. It does not contain the "upper" ESD diodes to clamp the inputs to V+.

    The LM397 Abs Max ratings show a maximum input voltage of 30V, with no references to supply voltage -similar to the LM339/393. So even with V+ at 0V, the input can go up to 30V (from V-) without damage.

    So most likely the LM397 is not damaged. Though we do not recommend doing this as part of normal operation. Current should be limited by a series resistor to 1mA or less, and an external clamp diode added between the inputs and V+.

    Regards,