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PMP40766: can the 47-ohm resistor RF1 under C11 be replaced with an ordinary resistor?

Links
Genius 11970 points
Part Number: PMP40766


Tool/software:

Hi，

   In the PFC circuit, can the 47-ohm resistor RF1 under C11 be replaced with an ordinary resistor? If not, can I directly short it to test the voltage across C11? Now, when the input voltage is 220VAC, the voltage across C5 is about 340V. D3 has been soldered, but the BOOST circuit in the middle has not been soldered. When testing the voltage across C11 at the rear stage, there is no output. Could you please explain what the reason might be?

Thank you.

  • +1
    TI__Mastermind 27145 points

    Hi Links,

    I recommend to use an NTC or similar if you want to replace RF1. This resistor ensures inrush current going into C11 is within an acceptable limit when AC is first applied to the board.

    With the PFC stage not populated, there is no path for the rectified AC voltage to make its way to C11. If you populate D3, you should see voltage on C11.

    Best Regards,

    Ben Lough