Greg,
We are using the AM186 on one of our boards with a 25MHz crystal.
What I did was put the crystal as close to the microprocessor and put a
ground plane under the crystal that covered the traces and filters for the
crystals on the top layer. I also made sure the traces where the same
length. It help do the reduce the harmonics to pass CE.
Ted
-----Original Message-----
From: Greg Olson [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 26, 2001 9:41 AM
To: Protel EDA Forum
Subject: [PEDA] EMC question
Hi all..
I've got a 2.5"x3.5" plug on daughterboard which contains my processor,
memory, flash, etc... The processor is a 20MHz AM186 driven by a 20MHz
crystal. I just had this system in for FCC EMC testing and found that the
20MHz crystal is bleeding its harmonics (especially 80MHz) all over
everything! It's getting onto the IO lines from the daughterboard to the
main board and from there onto just about every wire leaving the enclosure!
Can anyone give suggestions as to the best way to isolate this clock signal
in a relatively tight space? This is a 4 layer board, top layer signal, next
layer ground, then Vcc then signal again.
Thanks in advance,
Greg Olson
DSX Access Systems
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
* - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
