TPS65131: Output ripple too big

Alex Yeh

Expert 5475 points

Part Number: TPS65131

Hi team,

Would you help to review the schematic design? Customer reported the output ripple is too big. Thanks.

Regards,

Alex

over 3 years ago

0 Liaqat Khan over 3 years ago

TI__Mastermind 18550 points

Hi Alex,

The schematics did not come through in your post and I could not see them. Can you please re-attach?

Kind Regards,

Liaqat

0 Alex Yeh over 3 years ago in reply to Liaqat Khan

TI__Expert 5475 points

Hi Liaqat,

I attached the schematic again here. Please help to check and provide comments. Thanks!

Regards,

Alex

0 Liaqat Khan over 3 years ago in reply to Alex Yeh

TI__Mastermind 18550 points

Hi Alex,

I reviewed the schematics and one change that I could suggest is to tie PSP/PSN (pin 9/11) to GND instead of Vin that it is currently tied to. When PSP is tied to Vin, boost can go into PFM mode during lighter load and can have a significant amount of ripple. For ripple sensitive applications, we recommend to tie PSP/PSN to GND so that the device stays in constant frequency PWM mode which has a lower and much stable ripple.

Kind Regards,

Liaqat

0 Alex Yeh over 3 years ago in reply to Liaqat Khan

TI__Expert 5475 points

Hi Liaqat,

Thanks for your comment. Do you think increase L1/L2 to 5.6uH also help to reduce the ripple(reduce inductor p-p current)?

And do you have the design tool can share with me? Thanks.

Regards,

Alex

0 Liaqat Khan over 3 years ago in reply to Alex Yeh

TI__Mastermind 18550 points

Hi Alex,

Increasing inductor value may help slightly but I would not recommend it as it may have some impact on loop stability and all validation on TI evm was also done with 4.7uH. I still suggest to tie PSP/PSN to GND to achieve lower ripple.

Kind Regards,

Liaqat

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TPS65131: Output ripple too big