TPS62260: TPS62260 duty unstable

Alex Wu1

Intellectual 360 points

Part Number: TPS62260

Hi Expert

My customer use TPS62260 to buck 5V to 1.3V the function is ok but they find duty is unstable.

This phenomenon also can duplicate on TPS62260EVM-229 as attached file.

Could you help to clarify it.TPS62260 SW waveform.xlsx

over 5 years ago

0 Emmanuel Granatello over 5 years ago

TI__Expert 3465 points

Hello Alex,

it's my pleasure to support you.

Could you please share also the output voltage waveforms?

In the meantime I will try to duplicate the situation on the EVM.

0 Alex Wu1 over 5 years ago in reply to Emmanuel Granatello

Intellectual 360 points

Hi Emmanuel

Add Vout waveform in attached file thanks for your help.TPS62260 SW waveform-1.xlsx

0 Alex Wu1 over 5 years ago in reply to Alex Wu1

Intellectual 360 points

Hi Emmanuel

Do you find reason of this phenomenon.

0 Emmanuel Granatello over 5 years ago in reply to Alex Wu1

TI__Expert 3465 points

Hello Alex,

I have deeply investigated the stability of this device and I have reached the conclusion that the duty is stable, and what we see on the scope plot is just the internal oscillator jitter. Below you can see the bodeplot of the device working in PWM, to confirm my hypothesis. Also if you look carefully at your wfms you can notice that not only the duty changes but especially the sw period.

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Power management forum

TPS62260: TPS62260 duty unstable