TPS23751: The controller get damaged when the secondary load reaches 6W

Jozsef

Part Number: TPS23751
Other Parts Discussed in Thread: TL432, TLV431

Dear Team,

I'm using TPS23751 in my design. The design is similar like PMP111254.

Everything is fine until the secondary load reaches 6W. Whet it reach the 6W, the controller VDD and VSS pin goes to short circuit, and sometimes brings the primary FET to die.

I reviewd the schematic many times, I found some problem on it(I used TLV431 instead of TL432, and the soft start capacitor was in a wrong position). After I corrected these issues, the result is the same.

I temporary attached a 750k feed forward resistor, but it not resolved the issue.

I tryed WE 7491195112 instead of Colicraft POE300F-12L, but it not resolved the issue.

You can find the schematic below.

If you have any idea please let me know.

over 6 years ago

0 Darwin Fernandez over 6 years ago

TI__Mastermind 41800 points

Hi Jozsef,

Looking at the schematic, I don't see a series resistor on the bias diode. Also the feedback compensation does not look correct. There needs to be a series resistor and cap in parallel with C1014.

0 Jozsef over 6 years ago in reply to Darwin Fernandez

Prodigy 70 points

Hi Darwin,

Thank you for your reply. I'll try it, and I will come back with results.

0 Jozsef over 6 years ago in reply to Darwin Fernandez

Prodigy 70 points

Hi Darwin,

I placed the series resistor on bias diode, and the paralel R and C on C1014. The result is the same...any other idea?

0 Jozsef over 6 years ago in reply to Jozsef

Prodigy 70 points

Hi,

It seems, I found the main problem. Faulty I connected the input capacitor between Vdd and Vss. My PSE didn't went to fault, because I forced the output to current limit mode on it.

After I corrected this, connected the input capacitor between Vdd and GND(RTN), I've reached the desired 14 W output power. I incresed the load till 24 W without damage.

This is a great device, just like any other TI device.

Thank you.

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TPS23751: The controller get damaged when the secondary load reaches 6W