TPS23751: TPS23751 damaged...

Peter Tseng

Mastermind 6150 points

Part Number: TPS23751

Dear Sirs,

My customer's TPS23751 damaged after power on and they found the GATE pin shorted with GND.

Attached are schematics and VDD(yellow),VSS(green) waveform.

Please help to review their design and input your comments.

Thanks.

POE_V1_20190328_1328(FINIAL).pdf

over 6 years ago

0 Darwin Fernandez over 6 years ago

TI__Mastermind 41760 points

Hi Peter,

I believe R20 is 430 ohms. This is very large. Is the FET damaged as well? This should be 43 ohms

0 Peter Tseng over 6 years ago in reply to Darwin Fernandez

Mastermind 6150 points

Hi Darwin,

As customer feedback, they used 42.3ohm instead 430ohm on schematics.

What else point would you suggest to check?

Besides, they found the CE and RE test will fail while they did FCC certification.

The report as attached.

Did you have any suggestion to improve, also?

Thanks.

CE_IDTECH POE SPLITTER_LAN_LOAD1.2A_0.15-30Mhz_0412.Pdf

RE_IDTRCH POE splitter_1.2A LOADING_0.03-1GHz_0412.Pdf

0 Artem Rogachev over 6 years ago in reply to Peter Tseng

TI__Intellectual 1005 points

Hi Peter,

Darwin is out of office so I am filling in for him. I reviewed the schematic and it looks very similar to the EVM. Can you confirm that they copied the EVM? Only difference I noticed was that the VCC cap is ~16uF instead of 23uF.

In the initial waveform, where did they attach the scope GND? I am surprised to see the strange behavior on VSS after the part turns on.

If they are willing to do more testing, it would be good to test the following:
* Attach scope GND to VSS.
* Probes on RTN, VDD, VCC, and GATE.
* Trigger on VDD rising and capture waveform with ~50ms/div.

We can check if there is anything strange going on with Gate and VCC>

-Artem

0 Thomas Lewis over 6 years ago in reply to Artem Rogachev

TI__Expert 5615 points

Peter,

It has been 2 weeks since we last heard from you, do you still require our support for this thread?

If not hearing back from you by COB next Tuesday (4/30), we will consider this matter resolved and close the thread.

Thank you for your local support and promotion of PoE products from Texas Instruments,

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TPS23751: TPS23751 damaged...