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LM7480-Q1: Avoiding POR During Short-Circuit Testing

Antonio Fadhel
Genius 9410 points
Part Number: LM7480-Q1
Other Parts Discussed in Thread: LM7480

Hi Team,

My customer is having an issue during LM7480 short-circuit testing where the VS pin voltage drops below the POR threshold very briefly, causing system-level issues when restarting. They have the VS pin tied directly to the drain of the diode FET as recommended in the datasheet. As a potential solution, I am thinking adding an RC filter from the rail to the VS pin might help keep the device on (similar to the RC used for the load dump protection circuit).

Are there any potential downsides or design considerations for adding this RC to VS?

Thanks,

Antonio

  • 0
    TI__Guru 57737 points

    Hi Antonio,

    Can you please share your schematic and waveforms (when VS drops below POR threshold).

    You can try adding an RC at VS but the value of R needs to be very low unlike the case of  load dump protection circuit.

    In load dump protection circuit, the  duty of R is to limit the current flowing into zener at VS pin and help clamp the voltage at VS pin to below its recommended operating value. 

    For your case, you can try using an R value in the range 10 ohms.