TPS51120: TPS51120 PWM Double pluse issue

Hugo Liu

Genius 5095 points

Part Number: TPS51120

Hi Sir,

Our customer response the TPS51120 have PWM Double pluse issue as below,

We have cut-output not loading affect, we have try to short COMP2 to VFB2 not improve.

How can we improve this problem?

over 4 years ago

0 Hugo Liu over 4 years ago

Genius 5095 points

Hi Sir,

Update schematic,

this issue only on 3.3V power.

0 Yuchang Zhang over 4 years ago in reply to Hugo Liu

TI__Mastermind 18510 points

Hi,

some input for reference.

1, Check C16 spec whether can meet formula 19 in datasheet.

2, if item1 is ok, parallel a 20pf cap with R9 to try.

3, after 1 and 2, the issue still happen, let's review layout.

And by the way, check this happen only at light loading or both light loading and heavy loading..

Yuchang

0 Hugo Liu over 4 years ago in reply to Yuchang Zhang

Genius 5095 points

Hi Sir,

we are parallel a 20pf cap with R9 to try, Not significantly improved.
But we are change to 100pF Double pulse improved as below picture.
What's the Cap max value for TPS51120?

Add 100pF

Add 20pF

0 Hugo Liu over 4 years ago in reply to Hugo Liu

Genius 5095 points

Hi Sir,

Does TI have suggest Cap max value for TPS51120?

Hugo

0 Yuchang Zhang over 4 years ago in reply to Hugo Liu

TI__Mastermind 18510 points

Hugo,

I remembered I answered this question, but seems I failed to submit.

Generally suggest this cap not over 100pf.

Yuchang

0 Hugo Liu over 4 years ago in reply to Yuchang Zhang

Genius 5095 points

Hi Sir,

Thank you very much

Hugo

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TPS51120: TPS51120 PWM Double pluse issue