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TPS53353: TPS53353's output drops

Yang Wu
Expert 3370 points
Part Number: TPS53353


Hi Team,

Input:12V    Output:1V  15A(max)

The customer's issue is that output drops rapidly when the load is ON, resulting in the latter MCU rebooting. while if reduce the freq from 500kHz to 400kHz, the issue won't happen. So, what's the reason? customer can't reduce the freq and want to find the original reason to fix it.

according to the calculation, this design is in CCM, then how the freq affects the power level?

here is the SCH.

thanks!

Yang

  • 0
    TI__Prodigy 580 points

    Hi Yang, 

    I will review the schematic to see if I notice anything and will provide feedback in a few hours.

  • 0
    TI__Prodigy 580 points

    Hi Yang, 

    Here is my best guess at the issue from looking over the schematic:

    Please try lowering R873 to 3.01k Ohm
            - NOTE: with mixed caps on the output my ripple calculation is a best guess (the calculations are meant for ceramic only)
            - The theory here is that the ripple injection voltage is too low (it increases slightly when moving from 500 -> 400kHz)

    If step this does not solve the issue, can you please share waveforms and if possible layout so I can debug further? If needed you can email me directly.