TPS53319: Schematic Check - Startup dipping

Brian Antheunisse

Part Number: TPS53319

Hi guys,

My customer designed these two power supplies below, and had some boards built up. Some work fine, but one is suspect and may have a slow transient response. Both rails dip during startup, but then stabilize.

1V at 9A load, and 3.3V at 4A load. Turns out the true operating load is closer to 1V at 5A, and 3.3V at 3A.

My thoughts are: the inductor may be too low for the reduced current, is the ripple injection ok, is the output capacitance too low (under bias), would the current limit setting have any effect?

Thanks,

Brian

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

Brian.

We'll need to see waveforms that show your issue.

0 Brian Antheunisse over 7 years ago in reply to JohnTucker

TI__Expert 5305 points

John,

My customer isnt going to be able to capture the waveforms, so I guess can we change our question to being a schematic review, just to make sure there isn't anything fundamentally wrong with the component values chosen based on the updated load conditions? (is inductor sized incorrectly, etc)?

Thanks,
Brian

0 JohnTucker over 7 years ago in reply to Brian Antheunisse

TI__Guru**** 191445 points

Brian

Do you have any worksheet or other method such as Webench used to derive the external component values? usually I find that if I calculate without knowing how the customer derived the values, I get completely different values for everything. Let me know. We should probably move this off line as well.

0 Brian Antheunisse over 7 years ago in reply to JohnTucker

TI__Expert 5305 points

Turned out the issue was the input to the part, not the part itself. We took offline and issue is resolved.

Components were based in webench, and any components optimized for higher load conditions should work fine at lower load conditions.

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TPS53319: Schematic Check - Startup dipping