TLK110 / Capcitor for PFBOUT

user3893886

Other Parts Discussed in Thread: TLK110

I have referenced the following topic, but I have an additional question about the capacitor.

http://e2e.ti.com/support/interface/ethernet/f/903/p/335778/1171952.aspx#1171952

It is recommend to place 10uF and 0.1uF capacitors to pin PFBOUT of TLK110 device. The capacitance between 2 capacitor is difference 100 times. It means that antiresonant frequency will occur at about frequency 15MHz.

Is there any solution to avoid this antiresonant frequency?
Will it be better if I use one 0.1uF capacitor and a Feed Through Capacitor (ex : Murata NFM21PC105B1A3) at the output before connect to PFBIN1, PFBIN2?

Best Regards

Christ

over 10 years ago

0 Patrick OFarrell over 10 years ago

TI__Mastermind 31600 points

Christ,

The 10uF capacitor on PFBOUT is required to maintain the stability of the on-chip regulator. The combination of the 10uF and an 0.1uF capacitor has been seen to work without issues, but I don't see any problems with adding a 1uF capacitor also. Presumably the addition of the 1uF feed through capacitor would only improve the power supply response.

Patrick

0 user3893886 over 10 years ago in reply to Patrick OFarrell

Prodigy 110 points

Hi Patrick,

Thank you very much for your answer. I will evaluate the noise at PFBIN1,PFBIN2 pin including the case with/without feed through capacitor if possible.

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TLK110 / Capcitor for PFBOUT