TPS53355: VREG decrease rapidly when load current increase

Duan Wu

Prodigy 100 points

Part Number: TPS53355
Other Parts Discussed in Thread: TPS54KB20, TPS548B23, TPS548A23

Hi;

We found the tps53355 VREG decrease as load current increase:

12A LOAD, VREG is about 4.89V:

15A LOAD, VREG is about 4.31V, and some ripple appeard:

20A, VREG dropped to 4.37V, the chip output totally wrong

Could you please help us to fix this problem?

THX!

Donald

24 days ago

0 Jonathan Humphries 23 days ago

TI__Intellectual 1640 points

Hi Donald,

Calan will get back to you on this between this week and next week.

0 Calan Elaya 23 days ago

TI__Genius 16585 points

Hi Donald, can you provide the schematic so I can take a look.

Thanks,

Calan

0 Duan Wu 23 days ago in reply to Calan Elaya

Prodigy 100 points

sure, here it is:

sorry, I don't know how to upload a pdf file, so i upload a jpg file.

Donald

0 Duan Wu 23 days ago in reply to Calan Elaya

Prodigy 100 points

sure, here it is:

sorry, I don't know how to upload a pdf file, so i upload a jpg file.

Donald

0 Calan Elaya 22 days ago in reply to Duan Wu

TI__Genius 16585 points

Thanks Donald, allow me some time to look into this

Thanks,

Calan

0 Duan Wu 21 days ago in reply to Calan Elaya

Prodigy 100 points

Hi, Calan;

I saw this on the forum:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1563156/tps53355-question-of-tps53355dqpr-current?tisearch=e2e-sitesearch&keymatch=TPS53355#

And I changed my fSW to 250kHz, it worked! Now the output current can reach 15A, more than we need!

I just wonder what the reason is, could you please give me a answer?

THX!

Donald

0 Calan Elaya 21 days ago in reply to Duan Wu

TI__Genius 16585 points

Hi Donald,

this sounds like an issue of inductor ripple and switching frequency. Decreasing the switching frequency increases the inductor ripple which allows higher peak current. Inductor size may have needed to decrease to increase ripple and current achievement. Please let me know if you have any other findings.

The trip resistor sizing looks ok so that should not be the root cause of your issue.

Thanks,

Calan

0 Duan Wu 21 days ago in reply to Calan Elaya

Prodigy 100 points

Hi, Calan;

250kHZ is OK, we don't want to spend more time on this chip. We are considering choose a replacement for this application, could you please give me some advices?

THX!

Donald

+1 Calan Elaya 18 days ago in reply to Duan Wu

TI__Genius 16585 points

Hi Donald,

Please take a look at:

TPS54KB20
TPS548B23
TPS548A23

These are our latest devices that should suit this application. Let me know if these are of interest.

Thank you,

Calan

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TPS53355: VREG decrease rapidly when load current increase