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TPS65131-Q1: VCC drop

HouWei Pen
Prodigy 40 points
Part Number: TPS65131-Q1
Other Parts Discussed in Thread: TPS65131

When the terminal product is working,timing sequence of Chip pow er input port  is abnormal.

  • 0
    TI__Expert 4940 points

    Hi,

    I have notified our expert regarding this topic. Please expect a response by 5/15/20.

    Thanks,

    Costin

  • 0 in reply to Costin Cazana
    Prodigy 40 points

    OK,

       I have received it. I just accidentally pointed out that the problem has been solved. Can I receive a reply email in the future?

  • 0
    TI__Mastermind 18550 points

    Hello,

    TPS65131-Q1 has a soft-start on both boost and inverting converters that is place for about 1ms and from your scope plot, it appears that input supply sags ~1ms after it ramps up. So I think your input supply is not able to support enough current after the soft-start time of TPS65131-Q1 perhaps due to excessive inductance/resistance in the input supply path or not enough capacitance at the input supply pins of TPS65131-Q1. You can add more capacitance (10uF?) at the input supply close to TPS65131 and that may improve the sag you are seeing.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    Prodigy 40 points

    hi,Costin Cazana

       The countermeasure you provided has no effect.Does the input port of this chip power up with the current limiting Irish specification?At present, we have measured 1.3A Irush.

  • 0 in reply to HouWei Pen
    TI__Mastermind 18550 points

    Hello,

    As I mentioned earlier, both boost and inverting converters have a soft-start that last for approximately 1ms after being enabled. After this time, full current limit is in effect. One more thing you can do is to not enable both boost and inverting converters at the same time. Instead stagger them so that one is enabled first and reaches regulation before the second converter is enabled. This will reduce the input supply current demand. Beyond this, input supply needs to be able to provide enough current so that it does not sag.

    Kind Regards,

    Liaqat