LM76202-Q1: OVP doesn't work.

Hi Tatsuya,

Thanks for reaching out!

Is there any load during the test? if not, can you add and retest. 

Have you further increased Vin (say 40V or 44V) to check whether OVP is tripping..? 

Please share a test waveform like below

Best regards,

Rakesh

Hi Rakesh,

Thanks for the reply.
Please find attached the waveforms.
I am testing with the load connected.
I would be grateful for your advice.

Hi Tatsuya,

Thanks for the test waveform. I am wondering.. Is it happening on all boards ?

Can you please check whether voltage at pin-5 is crossing 1.225V. Please check right at device pin and also check the solderability of the device.

Best Regards,

Rakesh

Hi Rakesh

Thanks for the reply.
We have made 20 prototypes and checked several of them and the defects are all trending.
We have obtained the OVP waveforms, please check them.
Soldering does not seem to be a problem.
Please advise on this matter.

Best regards,

Tatsuya ishikawa

Hi Tatsuya,

It is surprising.

Can you share lot code (LTC) details to check. May be we need to submit the unit for FA to understand.

Best Regards,

Rakesh

Hi Rakesh

Thanks for the reply.

Please check the lot code shared below.

Best regards,

Tatsuya Ishikawa

Hi Rakesh-san,

This is Itoh, AFAE supporting Ishikawa-san.

We don't want to submit units for FA at this moment because we still suspect application issue.

This issue is happening 20 units out of 20 units on the prototype.

I asked him for POR test. The device started to pass when the input voltage is  ~7.1V, which is different from the POR threshold described in the datasheet (4V).

Do you happen to have any idea what is happening?

I can send you the layout and POR waveform, and RTN node voltage if you want.

Regards,

Itoh 

Hi Itoh-san,

Understood.

Please email me the full schematic and layout files for review.

Best Regards,

Rakesh