STPCI2 STMicroelectronics, STPCI2 Datasheet - Page 92

• Manufacturer Part Number: STPCI2
• Description: STPC ATLAS DATASHEET - X86 CORE PC COMPATIBLE SYS
• Manufacturer: STMicroelectronics

DESIGN GUIDELINES
6.4. PLACE AND ROUTE
6.4.1. GENERAL RECOMMENDATIONS
Some STPC Interfaces run at high speed and
need to be carefully routed or even shielded like:
1) Memory Interface
2) PCI bus
3) Graphics and video interfaces
4) 14 MHz oscillator stage
6.4.2. PLL DEFINITION AND IMPLIMENTATION
PLLs are analog cells which supply the internal
STPC Clocks. To get the cleanest clock, the jitter
on the power supply must be reduced as much as
possible. This will result in a more stable system.
Each of the integrated PLL has a dedicated power
pin so a single power plane for all of these PLLs,
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RECOMMENDATIONS
ground pad
Figure 6-20. Shielding signals
Issue 1.0 - July 24, 2002
All clock signals have to be routed first and
shielded for speeds of 27MHz or higher. The high
speed signals follow the same constraints, as for
the memory and PCI control signals.
The next interfaces to be routed are Memory, PCI,
and Video/graphics.
All the analog noise-sensitive signals have to be
routed in a separate area and hence can be
routed indepedently.
or one wire for each, or any solution in between
which help the layout of the board can be used.
Powering
capacitances is enough. We recommend at least
2 capacitances: one 'big' (few uF) for power
storage, and one or 2 smalls (100nF + 1nF) for
noise filtering.
ground pad
these
ground ring
shielded signal line
shielded signal lines
pins
with
one
Ferrite
+