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LMZ10500: over current waveform and behavior

Amos Chen
Prodigy 245 points

Part Number: LMZ10500

Hi Sir,

Please help explain the OCP waveform for LMZ10500

I increased the I_load slowly by electronic load until OC.

What is the LMZ10500 behavior in area 1?

LMZ10500 will auto retry (area 2) if in the OCP condition, right?

Thank you.

Amos

  • 0
    TI__Guru 50120 points
    Hi Amos,

    What is the X(time/div) and Y(volts/div) scale for these two scope plots? How long is the time duration of behavior 1?

    When OCP is tripped the part will turn the PFET off until the next switching cycle. During this time if the load pulls the output voltage down and feedback falls below 0.375V, short circuit protection is engaged. This is evident in your second waveform where the output voltage drops and hiccup mode is initiated.

    Regards,
    Jimmy
  • 0 in reply to Jimmy Hua
    TI__Mastermind 19911 points
    Hello Amos,

    As Jimmy mentioned, the hiccup mode of operation in output short circuit is triggered by the feedback signal falling below the 0.375V threshold.
    The behavior in "area 1" (using your naming convention from above) is cycle by cycle current limit behavior. This is the OCP behavior prior to feedback falling below the 0.375V threshold.

    Cheers,
    Denislav