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UCC28711: Recommendation connection for NTC Pin to increase Noise Immunity

Chetan Patel
Prodigy 130 points
Part Number: UCC28711

Dear Sir,

We are using UCC28711 IC in one of our Product having following specification.

Input Voltage : 400 to 750VDC

Output Voltage : 110V @ 1A

Topology : Flyback

NTC Pin kept open.

Currently we are facing issue at side of random reset of power supply due to noise and we want to know that if NTC pin is open is there any chanse to reset operation of UCC28711 IC?

Is there any recommendation circuit  for NTC pin to increase  noise immunity ?? currently  have kept it open.

Thanks in advance,

Regards,

Chetan Patel

.

  • 0
    TI__Mastermind 27135 points

    Hi Chetan,

    Generally, the NTC pin can be kept open without issue. If noise is coupling onto the pin, it theoretically could pose some problems however. You could try hanging a 20kΩ resistor on the pin to ground and put a small cap (few pF) in parallel to the resistor to see if the behavior improves. I would also suggest looking at the AUX winding voltage to get a sense as to what the VS pin is seeing. For PSR flybacks, any irregularities on the VS waveform can lead to problems achieving stable and reliable operation.

    Best Regards,

    Ben Lough