TPS54339: Output debounce when Vin drop

Gary Teng

Part Number: TPS54339

Hi Sir,

My cusotmer use TPS54339 for 12V to 5V application.

Please check the waveform below. The left pic is the waveform as about circuit. The right one modify C85 to resistor for changint EN voltage level.

Would you please helping to check why the debounce output shown? Removing C85 from system has the similar waveform as the left pic.? Thanks for your kindly help.

Regards,

Gary Teng

over 1 year ago

0 Zixu Wang over 1 year ago

TI__Expert 8100 points

Hi Gary,

I will check it and give you feedback later!

BRs

Zixu

0 Gary Teng over 1 year ago in reply to Zixu Wang

Genius 5520 points

Hi Zixu,

Any comment about our question?

Regards,

Gary

0 Zixu Wang over 1 year ago

TI__Expert 8100 points

Hi Gary,

Root cause of shown behavior may be following reason: when power down speed of Vin is slow, stored power in Cin may dissipate to Vin line and charge Vin above UVLO when Vin drops down across UVLO, enabling converter. At this moment, you could see Vout re-power up during power down process.

When you change EN network to make converter shutdown earlier, you will not see the phenomenon.

BRs

Zixu

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TPS54339: Output debounce when Vin drop