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LM74610-Q1: Negative voltage at Cathode

Masatoshi Oguri
Expert 4780 points
Part Number: LM74610-Q1
Other Parts Discussed in Thread: LM43602-Q1

Hello,

I am seeing a negative voltage at Cathode of LM74610-Q1 in reverse battery condition. Specifically, Anode is at -13.5V.

The negative voltage is at -0.45V caused by the reverse leakage current (ILKG) from Cathode to Anode of typically 60uA. This is all right for LM74610-Q1, but is a serious problem for LM43602-Q1, which is in the downstream. The negative voltage is out of the rating of LM43602-Q1 at -0.3V.

Do you have any good idea to avoid this situation?

Thanks.

Regards,

Oguri

  • 0
    TI__Expert 5940 points

    Oguri,

    60uA is right out of the DS ES table.  High spec at -13.5v is 110uA.  That is just what the device does, 60uA is a fairly low value. Customer input impedance (~7.5k ohm) needs to be lowered or clamped to reduce the -0.45v to an acceptable level.  Either a 2.5k-4k load resistor (depending on consistencey of customer input Z) or a Schottky cathode Vout anode gnd to reduce voltage impact.

    Brian