Intel Pentium 4 User Manual

Layout Review Checklist
R
Intel
®
Pentium
®
4 Processor / Intel
®
850 Chipset Family Platform Design Guide 269
16 Layout Review Checklist
This checklist highlights design considerations that should be reviewed prior to manufacturing a
motherboard that implements an Intel 850 chipset. The items contained within this checklist
attempt to address important connections to these devices and any critical supporting circuitry.
This is not a complete list and does not guarantee that a design will function properly. Beyond the
items contained in the following text, refer to the most recent version of the design guide for more
detailed instructions on designing a motherboard.
16.1 Processor and System Bus
16.1.1 AGTL+ Signals
This section covers the address, Data, DSTBn/p#, ADSTBn/p# and common clock signals. Refer
to the processor datasheet for a system bus list, signal types and definitions.
√ Recommendations Reason/Impact/Documentation
• Trace width recommendation is 7 mils with
13 mil edge-to-edge spacing for all signals.
Trace spacing can be approximately 5 mils
within pin field.
• Refer to Section 5.3.
• Processor clock differential pairs should
have a minimum of 20mil spacing from
other signals.
• Data signal (D[63:0], and DBI[3:0]#) length
should be 2 inches – 10 inches pin-to-pin.
Data signals of the same source
synchronous group should be routed to the
same pad-to-pad length ±100 mils. Length
must be added to the motherboard to
compensate for package length differences.
• The length compensation will result in
minimizing the source synchronous skew
that exists on the system bus. Without trace
matching and length compensation flight
times between the data signals and the
strobes will result in inequity between the
setup and hold times.
• Refer to Chapter 2.
• A strobe and its complement (DSTBP[3:0]#
and DSTBN[3:0]#) should be routed within
±25 mils of the same pad-to-pad length
• The impact of this recommendation causes
the strobe to be received closer to the
center of the data pulse, which results in
reasonably comparable setup and hold
times. It is recommended to simulate skew
in order to determine the length that best
centers the strobe for a given system.
• Refer to Chapter 2.

Intel Pentium 4 Specifications

General

Brand	Intel
Model	Pentium 4
Category	Computer Hardware
Language	English