Re[2]: Spread Spectrum Clocking

[gstein@tricord.com]

        I find the clocking situation interesting...

        there is the letter of the law PCI spec-wise, and then there is the 
        defacto reality established by Intel.  Specifically, I'm referring to 
        use of PLLs on the PCI clock.  Intel's 960RP chip virtually requires 
        usage of a PLL, in fact the 960RP design guide calls for one.  The 960RP
        will be present everywhere as I2O becomes prevelant.  

        - Gary Stein
          Tricord Systems

______________________________ Reply Separator _________________________________
Subject: Re: Spread Spectrum Clocking
Author:  pci-sig-request@znyx.com at internet
Date:    1/31/97 2:18 PM


Ben,
     
This was discussed in depth here a while back. 
The conclusions:
1) Some mother boards do this.
2) It does not violate the PCI spec.
3) PCI cards can not use a PLL type (0 Tpd) of clock buffer chip, 
they would be in violation of the PCI spec if they did.
Hope this helps.
     
-Ivor
     
At 11:06 AM 1/31/97 -0800, you wrote: 
>Hello PCI Community,
>
>I've heard that there are systems out there 
>using 'spread spectrum clocking' technology 
>in order to pass FCC EMI testings.
>
>I would like to get some feedback on how common 
>this practice is done in the PCI world, especially 
>for the ones who build motherboards which
>provide PCI slots.
>
>Would this violate PCI specs in any way? 
>
>Thanks.
>
>- Ben -
>
>_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ 
>  Benson Cheung           (bcheung@adobe.com)
>  Adobe Systems Inc.
>  Printing & Systems Division
>  M/S  P05
>  303 Almaden Blvd.
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>
>
>
-Ivor
     
--------------------
standard disclaimer:
I speak for myself and my views may not be the same as my employer's. 
Ivor Bowden
Peritek Corp
phone: (510) 531-6500
FAX: (510) 530-8563
email: ivor@peritek.com
     
`H6