TPS23754: Output Current Issue

eunsung Ha

Part Number: TPS23754
Other Parts Discussed in Thread: PMP6812,

Hello, Team

I have implemented a power circuit using TPS23754. The input power is solely from a 54V adapter, and the circuit demands an output of 12V 2.5A.

The issue I am facing is that although the output voltage is 12V, when the power reaches around 5W(54V,0.09A), the FET(U20) starts to heat up significantly, reaching temperatures as high as 100 degrees Celsius. The VC measures 18V, while the GATE receives 12V. VB shows a reading of 5.1V.

I have attempted to modify the APD and PPD pins by attenuating the input voltage through resistors, but the problem persists, and I haven't found a solution.

I would appreciate your assistance in troubleshooting this issue.

over 2 years ago

0 Diang Xing over 2 years ago

TI__Mastermind 37031 points

Hi Eunsung,

Thanks for reaching out.

The transformer you applied is used for forward converter. You used a flyback converter which needs a flyback transformer which can store energy. Using forward transformer may easily cause flux density saturated.

You can refer PMP6812 (https://www.ti.com/tool/PMP6812) which is TPS23754 based 12-V output flyback design.

Best regards,

Diang

0 eunsung Ha over 2 years ago in reply to Diang Xing

Prodigy 10 points

I bought a TPS23754EVM-383 to check the signals on the pins of the TPS23754.

The GATE pin of the EVM board outputs 250KHz very normally. However, the GATE pin of our board outputs signals intermittently.

I'd be grateful if you could tell me why this is happening.

0 Diang Xing over 2 years ago in reply to eunsung Ha

TI__Mastermind 37031 points

Hi Eunsung,

The converter you designed applies the peak current mode control. I doubt that the forward transformer you chose is not suitable. It will cause the current ramp too fast to turn off the gate each cycle.

Please try with a flyback transformer.

Best regards,

Diang

+1 Diang Xing over 2 years ago in reply to Diang Xing

TI__Mastermind 37031 points

Hi Eunsung,

I will close this thread for now. Please reply or open a new thread if you have further questions.

Best regards,

Diang

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TPS23754: Output Current Issue