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LM53601-Q1: Hiccup Issue

Mark Ackerson
Genius 10190 points
Part Number: LM53601-Q1

Customer is having issues with TPS536015 going into hiccup mode on 10% of their board assemblies and not recovering.  The TPS536015 is used to generate a 5V supply that powers downstream regulators generating 3.3V, 2.5V and 1.2V.

Reducing the output capacitance on the downstream regulators resolves the issue.

What is the best way to work around this issue on the TPS536015 without reducing the output capacitance?

Could we use TPS536015 !RESET to drive the enable pins of the downstream Vregs to reduce startup current?

What about using an RC on the TPS536015 EN pin to extend startup time?

Please advise.

Thanks,
Mark

  • 0
    TI__Guru 57555 points

    I think that using the reset to enable the loads would be a good thing to try.

    That may allow the LM53601 to charge the caps without the added load of the other regs.

    Delaying the EN to the LM53601 would not help, since it is a digital pin and would only delay

    the time the reg starts wrt the EN signal.

    Unfortunately, this device does not have external soft-start; that would probably be the best way.

  • 0 in reply to Frank De Stasi
    TI__Genius 10190 points

    Hi Frank,

    Thanks for the response.  The customer has LM536015 !RESET connected to the EN pins of the downstream regulators.  Unfortunately they still see the issue.

    Besides reducing output capacitance do you have any other suggestions?

    Regards,
    Mark

  • 0 in reply to Mark Ackerson
    TI__Guru 57555 points

    Reducing the cap load or using a device with adjustable soft-start are the only things

    I can think of.  Some of our devices will prevent hiccup until the output voltage is at 40% of 

    final.  That kind of device might help.