TPS53353: tps53353 1V output problem

Radomir Dzakula

Prodigy 55 points

Part Number: TPS53353

We have weird behavior.

Output remains for 1v just a coup of sec then leaves.

It gets back to 1v when the input voltage drops from 12v to around 7V.

If it go back to 12V its output is at 0V.

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

Can you post some waveforms? be sure to include the SW (LL) node.

0 Radomir Dzakula over 7 years ago in reply to JohnTucker

Prodigy 55 points

0 Radomir Dzakula over 7 years ago in reply to Radomir Dzakula

Prodigy 55 points

This is captured on LL pins.

0 Radomir Dzakula over 7 years ago in reply to Radomir Dzakula

Prodigy 55 points

And this one is captured after addition of the modification of the 47K+0.1uF + 1nF bridged on the inductance

0 JohnTucker over 7 years ago in reply to Radomir Dzakula

TI__Guru**** 191445 points

Radomir,

Can you tell me the timescale and amplitude of those waveforms?

0 Radomir Dzakula over 7 years ago in reply to JohnTucker

Prodigy 55 points

2V/div and 50ms/div

2V/div and 20us/div

It is in the pic, top left yellow, I hope it can be seen after upload.

0 JohnTucker over 7 years ago in reply to Radomir Dzakula

TI__Guru**** 191445 points

The time between pulses is about 36 msec. in the first picture. since you wave 2.8 msec SS time selected, that corresponds to the OCP protection hiccup time. It appears you are activating over current protection. Can you check the inductor current at start up? Certain electrolytic capacitors can have very low impedance when completely discharged. They may be drawing very large current at start up. That is where I would look first.

0 JohnTucker over 7 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Radomir,

Did you resolve this? I will mark this as resolved. You can re-open it by responding.

Thanks,

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TPS53353: tps53353 1V output problem