Intel 41110 manual PCI General Layout Guidelines, PCI Resistor Compensation

PCI-X Layout Guidelines

•Bus parking on last PCI agent or the bridge.

By default, the arbiter parks the bus on the bridge and drives the A/D, C/BE# and PAR lines to a known value while the bus is idle.

8.2.1PCI Resistor Compensation

Figure 15 provides the recommended resistor compensation pin termination for the PCI A bus.

Figure 15. PCI RCOMP

RCOMP

100 Ω – 1%

B2718 -01

8.3PCI General Layout Guidelines

For acceptable signal integrity with bus speeds up to 133 MHz it is important to PCB design layout to have controlled impedance.

•Signal traces should have an unloaded impedance of 60 +/- 10% Ω.

•Signal trace velocity should be roughly 150 – 190 ps/inch

There are a couple of general guidelines which should be used when routing your PCI bus signals:

•Avoid routing signals > 8”.

•The following signals have no length restrictions: A_INTA#, A_INTB#, A_INTC#,

A_INTD#, and TCK, TDI, TDO, TMS and TRST#. Most PCI-X signals are timing critical. These signals have length restrictions for propagation, setup, and hold requirements. Table 6 shows the PCI-X signals.

Intel® 41110 Serial to Parallel PCI Bridge Design Guide 31