Intel 31154 manual Pull-Up/Pull-Down Terminations Sheet 4 of, Signal, Comments, Hot Swap

Terminations
Table 5.	Pull-Up/Pull-Down Terminations (Sheet 4 of 9)
Signal		Pull-Up/Pull-Down or Termination (See Note 1)	Comments
		When the internal clock of the 31154 is used, pull
		high to VCC33 through an external 8.2 KΩ resistor.
		When an external clock source is used, tie to GND
		through a 330 Ω external resistor. All secondary
S_GCLKOEN		clock outputs (S_CLKO[8:0] and S_BRGCLKO)
		asynchronously tristate.
		When an external clock source is used, tie
		S_CLKOEN[3:0] to a stable value. Refer to
		S_CLKOEN[3:0], below.
		These are strapping pins to enable or tristate	NOTE: This strapping is meaningful only when
		S_CLKO[8:0] after reset.	S_GCLKOEN is pulled high.
		• To enable all S_CLKO[8:0], pull each	When external clocks are used, tie S_GCLKOEN
S_CLKOEN[3:0]		S_CLKOEN[3:0] pin to 3.3 V through an	low and tie S_CLKOEN[3:0] to some stable value
		external 8.2 KΩ resistor.	(0000b, for example).
		• To selectively disable some of the
		S_CLKO[8:0], refer to 31154 Control
		Register 2, bits[8:0].
Hot Swap
		For Hot Swap:
HS_ENUM#		• Connect the interrupt input pin to the host.
		When not using Hot Swap:
		• NC (there is a weak internal pull-up).
		For Hot Swap:
HS_LSTAT		• Connect to cPCI ejector switch.
		When not using Hot Swap:
		• Tie low to GND.
		For Hot Swap:
HS_LED_OUT		• Connect to cPCI blue LED.
		When not using Hot Swap:
		• NC
		For Hot Swap:
		0 = The 31154 retries any Type 0 configuration
		cycles addressed to it until serial ROM
		preload has completed (default)	0 = Tie low to GND.
HS_SM		1 = The 31154 ignores (causes master abort) any	Ω
		Type 0 configuration cycles addressed to it	1 = Pull high to 3.3 V through an external 8.2 K
			resistor.
		until its serial ROM preload has completed.
		When not using Hot Swap:
		• Tie low to GND.

NOTES:

1.The recommended value for pull-up resistors for PCI applications is 5.6 KΩ (note that the minimum value for PCI 3.3 V signaling RMIN = 2.42 KΩ, RTYP = 8.2 KΩ, as per the PCI Local Bus Specification, Revision 2.3, section 4.3.3).

2.The recommended value for pull-up resistors for PCI-X applications is 8.2 KΩ. For PCI-X, the minimum pull-up resistor value is 5 KΩ, as per the PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0b, section 9.7.

3.For plug-in card implementations, the pull-up must be on the motherboard.

4.Connect PVIO and SVIO pull-up resistors to 5 V or 3.3 V power supply through an external resistor—25 Ω (5 V) or

0 Ω (3.3 V), depending on the signaling level of the primary/secondary PCI bus. Refer to the power-sequencing guidelines in Section 8.2 on page 58.

22 Intel® 31154 133 MHz PCI Bridge Design Guide Design Guide