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LM25069 Negative Bias on Vin to Sense

Al Baetz
Prodigy 10 points
Other Parts Discussed in Thread: LM25069

We are using the LM25069 and may have a senario where Vin may go negative relative to the Sense pin. We expect to be within the -0.3V to +0.3V absolute maximun specifications in the datasheet. What is the effect on the LM25069 and Gate voltage during this negative bias period?

The block diagram in the datasheet has cross coupled diodes between the Vin And Sense pins. Do these limit the voltage between these pins to -0.3V to +0.3V.

Thanks,

Al Baetz

Pi-Coral, Inc.

  • 0
    TI__Genius 12621 points

    Hi Al,

    Those anti-parallel diodes are a property of the current sense amplifier. They are the reason we spec the +/-0.3V abs_max. This may be a little conservative, as they should begin to conduct closer to 0.6V typical. However, the goal is to keep these diodes OFF, thus preventing large current draw through the IC.

     

    The LM25069 should be ok if the voltage goes negative relative to the sense pin, but remains below -0.3V.

     

    The GATE should continue to be high, it does not detect this negative voltage within the sense amplifier and thus should not shut off.

     

    Edit: By the way, welcome to the forums! We're glad to have you here and thanks for considering TI products for your design.

     

    Thanks,

    Alex