This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC27511: The max voltage on IN+ pin

Part Number: UCC27511
Other Parts Discussed in Thread: PMP22075

Hi Experts,

In PMP22075 reference design, what's the purpose of the diode and resistors? 

Since the transformer winding voltage is quite high, it is applied to IN+ pin through resistors, how much voltage is allowed on IN+ pin? How to calculate the resistors?


  • Hello,

    Thanks for reaching out.

    INx pin voltage should not exceed according to datasheet recommended operating conditions.

    The clamp to VDD should limit the voltage range to the specified range.

    The resistors and diodes are typically used on the output stage to optimize the turn-on/off the gates, it is unclear why the design use this configuration on the INx pins but we need to ensure that INx is within the 18V recommended operating range.