Intel 41210 manual PCI-X Clock Layout Requirements Summary, PCI-X Layout Guidelines, Parameter

PCI-X Layout Guidelines

Table 8.	PCI-X Clock Layout Requirements Summary
	Parameter	Routing Guidelines
	Signal Group	PCI Clocks B_CLKO[6:0], A_CLK[6:0]
	Reference Plane	Route over unbroken ground or power plane
	Stripline Trace Width	4 mils
	Stripline Trace Spacing: Separation between two	25 mils center to center from any other signal
	different clock lines, “d” clock lines
	Stripline Trace Spacing: Separation between two
	segments of the same clock line (on serpentine	25 mils center to center from any other signal
	layout), “a” dimension
	Stripline Trace Spacing: Separation between clocks	50 mils center to center from any other signal
	and other lines
		All 41210 Bridge Output Clocks B_CLK0[6:0] and
		A_CLK[6:0] connected to devices must be length
	Length Matching Requirements	matched to 0.1 inch of each other.
		The clock feedback line lengths from A_CLKOUT to
		A_CLKIN and B_CLKOUT to B_CLKIN should be
		length matched to all other clock lines within 0.1”.
	Total Length of the 41210 Bridge PCI CLKs on the	10” -14”
	adapter card
		Connect A_CLKIN to one end of a 22Ω +/- 1% resistor
	A_CLKIN, B_CLKIN Series Termination	and the other end connected to A_CLKOUT and
		connect B_CLKIN to one end of a 22Ω resistor and
		the other end connected to B_CLKOUT
		Each of the clock outputs A_CLKO[6:0] and
	A_CLK[6:0], B_CLK[6:0] Series Termination	B_CLK[6:0] should have series 22Ω resistor located
		within 500 mils of the 41210 Bridge clock output.
	Routing Guideline 1	Point to point signal routing should be used to keep
		the reflections low.
	Routing Guideline 2	Minimize number of vias

Intel® 41210 Serial to Parallel PCI Bridge Design Guide 37