Re[2]: [SI-LIST] : Power Supply Noise Filters

ed_crean@smtplink.spectrian.com
Tue, 31 Mar 98 12:22:05 -0800

The best low frequency filter is a regulator. Having said that, additional
regulation can be accomplished using an LC low pass filter. Use a low dcr
inductor (from coilcraft or toko) rated for your current. The capacitor should
be low ESR. The filter can be simulated on PSPICE. Damping capacitors may be
required to prevent resonance.

Ed Crean
Spectrian Corp

______________________________ Reply Separator _________________________________
Subject: Re: [SI-LIST] : Power Supply Noise Filters
Author: Khalid Ansari <kansari@lsil.com> at SMTP
Date: 3/30/98 2:56 PM

Hi Michael,

Thanks for your response on the Power supply email that I had sent
earlier. Actually, I didn't make myself very clear, I apologize. I am
looking for a noise filter that I can layout on my board to dissipate
any noise generated by an external +5V raw, PC, power supply coming into
a regulator that I am using to generate a +2.5V output. Your response
regarding use of regulators in this case is helpful, but I will really
appreciate if you could suggest a noise filter I could use.

Thanks
Khalid

Michael T Zhang wrote:
>
> Text item:
>
> You basically have two choices: linear regulator or switching regulator.
> Linear regulator would have less than 50% efficiency based on your
> input/output voltage ratio. So power consumption on the regulator might
> be an issue if the current is high. However, it would filter out much of
> the input noise (high audiosusceptibility). Switching regulator on the
> other hand has good efficiency and high audiosusceptibility, but
> introduces noise at the output due to its own switching. If noise is
> critical, you can use multiple-stage low-pass filters. Common practices
> are using linear for low-power applications; and switchers for
> high-power ones.
>
> -Michael Zhang

>
> Hello everybody,
>
> I have a regulator on my board that requires a +5 V input which in
> turn provides +2.5 V to my circuitry. Would you guys have any recommendation
> on any power supply noise filters that I can use to minimize any noise
> generated by my +5V external power supply. I would appreciate any
> inputs on what kind of power supply I should use.
>
> Thanks
> Khalid
> ____________________________________________________________________
>
> Khalid Ansari LSI Logic Corporation
> Applications Engineering 1551 McCarthy Blvd
> Tel: 408.954.4965 MS G-750
> Fax: 408.433.2840 Milpitas CA-95035
> ____________________________________________________________________
>
>
____________________________________________________________________

Khalid Ansari LSI Logic Corporation
Applications Engineering 1551 McCarthy Blvd
Tel: 408.954.4965 MS G-750
Fax: 408.433.2840 Milpitas CA-95035
____________________________________________________________________