TPS544B20: PGOOD glitch issue

user1874945

Part Number: TPS544B20

Hi Sir or Madam,

We met a problem in using TPS544B20. There is a glitch on PGOOD which is causing the system reboot. From the datasheet, the PGOOD windows is +/-12.5% as default value.

May I ask how the IC internally sets this +/-12.5% window? which signal (or signals) is used? Is it using the FB pin voltage and comparing with a reference voltage?Per the below waveform, seems the PGOOD is asserted before the output voltage is really out of +/-12.5% window?

Thanks,

over 7 years ago

0 Mathew Jacob1 over 7 years ago

TI__Expert 5910 points

Hi,

Over Current Fault

Soft Start Done

Enable

All of these can trigger PG apart from the UVLO and OVP situation.

Regards,
Mathew

0 user1874945 over 7 years ago in reply to Mathew Jacob1

Intellectual 300 points

Hi Mathew,

We found the reason. It is caused by the sharp falling edge of the AVS signal(6us from 786mV to 576mV). Please refer to the below picture 1.

Could we do change on FB pin like picture 2 shows? Suppose it will not affect the compensation loop. Could you help to check if there is any side effect?

0 Mathew Jacob1 over 7 years ago in reply to user1874945

TI__Expert 5910 points

Hi,

This method looks good.

Regards,

Mathew

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TPS544B20: PGOOD glitch issue