[SI-LIST] Re: PI Analysis about Core Power Supply
- From: Mike Brown <bmgman@xxxxxxxxxx>
- To: zhang_kun@xxxxxxxxxx
- Date: Sun, 08 May 2005 07:43:12 -0500
Zhangkun wrote:
>Dear All
>In current work, I am studying core power supply. The voltage of core power is
>very low (0.9V-1.2V) and the power consuming is very high (dozens of Amperes).
>There is often power integrity problem in the frequency domain from 10MHz to
>20MHz. The solution is very easy that discrete caps should be added on the PCB.
>
>
>
Zhangkun, in that frequency range, you will probably find that software
loops are the culprit. The program loop(s) are switching from doing
something that consumes power to something that doesn't. Like maybe
accessing memory for a while, then running out of cache for a while.
That may not be a good example for core power, specifically, but some
sort of cyclic activity due to software can cause the frequencies that
you mention.
Mike
>My problem is that the PI problem is found out until the first edition has
>been produced. Then the decoupling caps is determined. I want to determine the
>decoupling caps before the first edition is produced in order to quicken the
>design flow. Therefore, I should know the current noise source. I have been
>looking for the paper about how to get the core power consuming in IEEE
>electrical library. However, I have not found any useful paper.
>
>I hope I have express myself clear. Any advice is prefered.
>
>Best Regards
>
>Zhangkun
>2005.5.8
>
>
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