TPS53647: VR fault fired after ENABLE the chip without load

diverger

Part Number: TPS53647

HI,

We designed a TPS53647 multiple phase buck board based on the schematic given in the datasheet. With no load connected, after ENABLE the chip, we got the OTP fault (Both the register and the VR_FAULT pin report it). It seems this is the same situation with one previous post .

Any help?

Thanks.

over 4 years ago

0 Chasel Chen over 4 years ago

TI__Expert 5830 points

Hi Diverger,

It looks power stage fault is triggered. Which power stage is on the board right now?

Can you also probe SW1/VOUT/EN/CSP1 to further understand the issue?

Thanks

0 diverger over 4 years ago in reply to Chasel Chen

Expert 1275 points

The measured signals as below:

0 Chasel Chen over 4 years ago in reply to diverger

TI__Expert 5830 points

Thanks for the waveform, it looks VOUT is not ramping up. Can you please show me the schematic for review?

0 diverger over 4 years ago in reply to Chasel Chen

Expert 1275 points

Hi,

What's strange is, the PWM output can go to 7MHz, is it possible? I suspect the so high switching frequency boost the temperature of the power stage, then cause the over temperature fault. What can cause the chip to output a so high PWM frequency?

The detailed wave shows the frequency as below:

Thanks.

0 Chasel Chen over 4 years ago in reply to diverger

TI__Expert 5830 points

Got you, the PWM firing with minimum off time which is not normal, can you please send us the schematic for review? If it is confidential, you can send it via email box.

Thanks

0 Chasel Chen over 4 years ago in reply to Chasel Chen

TI__Expert 5830 points

Hi Diverger,

I'll close this thread because it looks the issue related to VSP/VSN routing which not routes as differential pair after offline discussion.

Thanks

Chasel.

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TPS53647: VR fault fired after ENABLE the chip without load