TPS563203: Failing in RE test

Hi Mitesh,

Will check and get back to you!

Regards,

Usha.

Hi Mitesh,

Is this RE test result is including all the three bucks or particular buck?

Try adding RC snubber circuit to SW to GND with 30ohm (recommended 2W resistor),33pF.

Regards,

Usha.

Hi Usha,

This result is including all 3 bucks.

We have tried the same, but no success.

Hi Mitesh,

Have you tried keeping snubber on all the three bucks?

Yes

1. What are the values of RC?

2. How much amplitude did it decrease after keeping snubber?

We tried with R = 5ohms & C=680pF, in all 3-buck converter, no change was observed.

Is there any calculation for the same?

Hi Mitesh,

To understand which buck is failing please do one by one RE test.

First test on first buck converter then turn on second buck and then turn on last buck converter by keeping before bucks on!

Regards,

Usha.

Hi Usha,

Did the same thing, it is failing because of 2.5V & 1.2V buck converter.

Hi Usha, also please suggest what else can be done apart from RC snubber on SW?

Kindly let me know any more information required from my side.

We are planning to do RE test in external lab day after tomorrow.

Hi Mitesh,

If snubber is not improving, try adding 220pF+100nF capacitors very close to IC, just before input capacitors and also at input sense.

This is snap for 1.2V with load, is it because of this RE is failing, since it is going upto -2.6V. Kindly suggest.