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TIDA-010015: Why does it use TLV171 in TIDA-010015 schematic

Part Number: TIDA-010015
Other Parts Discussed in Thread: UCC28064, , TLV171

Dear Sir,

I review UCC28064 to design 450W SMPS. and I find 500W reference design using UCC28064.

I have a question in the TIDA-010015 as below.

1.Why does it use TLV171? inrush protector?

  • Hello Dexter,

    I reviewed the schematic and TLV171 is used to control a current inrush limiting resistor (RF1). During power up this resistor is in series with the bulk capacitor. When the bulk capacitor is charged up to 109.5V FET Q10 is turned on and current limiting resistor RF1 is shorted out.

    If this resistor was not added the only think limiting the current would be the bulk capacitor’s (C1) ESR.

    If the ESR of this cap was 1 ohm at 109.5V this would be a 109.5A, which might cause the boost diode D1 to fail or even the bridge rectifier.