[SI-LIST] a problem about PLL bypass
- From: lu Haizhao <luhaizhao@xxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 31 Mar 2003 14:30:37 +0800
Hi,all
In the Motolola's telecom controller XPC8260-200MHz's handbook,the
PLL bypass circuit is the following:
VDD _____
-------------|____|-----------------------VCCSYN
R | |
___ ___
___ 10uF ___ 0.1uF
| |
|____________|
|
|
GND
the R is 10 Ohm.
In the board,I use a ferrite bead instead of a resistance.This
ferrite bead has a resistance of 0.01 Ohm in steady current,and 60 Ohm
in 100MHz.
the problem is when the board is under -5=A1=E6 to =
-30=A1=E6=A3=ACsometime the
8260 can not boot up normally or can not boot up.and if you use a
resistance,not a ferrite bead,the problem will disappear.
Can someone tell me the cause? Thanks!
Regards,
Sean Lu
Huawei Technologies co.,Ltd=20
Shenzhen China=20
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