[SI-LIST] Re: Switching power supply Vs. Linear power supply for Processor Core and IO
- From: earl albin <earlalbin@xxxxxxxxx>
- To: V S <for_si2003@xxxxxxxxx>
- Date: Wed, 11 Mar 2009 11:31:56 -0500
Yes there is an upside for an SMPS, but potentially the linear could prove
more efficient (you figure the details). Typically a linear has a wide
bandwidth, either 0-dB or -3dB vs an SMPS which has many advantages when
used in high di/dt application. One obvious is that large bulk capacitors
are not required local (simplistic depends on board impedance). Another is
that an SMPS has significant noise either current fields and or electric
fields that could couple. The other is that swichers typically deliver
power, they can remove power as well by pumping somewhere else (won't get
into that). They don't, in a strict sense shunt power. So if you need
really good transient regulation/response where you attenuate both the
overshoot and undershoot, you need a shunt typically. (why used in DDR)
Though what is choosen should be the best choice considered the application
and tradeoffs. I can understand why "Linear power supply used for processor
cores and the mobile DDR RAMs," makes sense to me.
On Mon, Mar 9, 2009 at 5:59 PM, V S <for_si2003@xxxxxxxxx> wrote:
>
> I have seen mostly Linear power supply used for processor cores and the
> mobile DDR RAMs in the designs of embedded processor board systems.
>
> For power supply experts - do you see any specific reason not to use
> switching power supplies for processore cores or the low voltages IO ( like
> 1.8V in mobile DDRs) ?
>
> The gain from switching supply could be efficiency.
>
> Vikas Shukla
>
>
>
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