Intel 31154 manual Terminations4, Pull-Up/Pull-Down Terminations Sheet 1

Terminations

Terminations4

This chapter details all the recommended Intel® 31154 133 MHz PCI Bridge terminations required for the different operating modes.

The chapter provides the recommended pull-up and pull-down terminations for a 31154 layout. Table 5 lists these 31154 termination values. Note that for motherboards, the PCI Local Bus Specification, Revision 2.3 requires that the PCI signals provide the termination resistors.

Table 5.	Pull-Up/Pull-Down Terminations (Sheet 1 of 9)
Signal		Pull-Up/Pull-Down or Termination (See Note 1)	Comments
PCI Reset
P_RST#		Connect to bus RST# signal on primary PCI bus.
S_RST#		Connect to bus RST# signal on secondary PCI
		bus.
Primary PCI Signals
P_AD[31:0]		Connect to primary PCI bus AD[31:0].
		For 64-bit primary PCI bus:
		• Connect to the AD[63:32] bits of the primary
P_AD[63:32]		PCI bus.
		For 32 bit Primary PCI Bus:
		• Pull up through individual external resistors
		(see Note 2 and Note 3).
P_CBE[3:0]		Connect to the CBE[3:0}# bits of the primary PCI
		bus.
		For 64-bit primary PCI bus:
		• Connect to the CBE[7:4]# bits of the primary
P_CBE[7:4]#		PCI bus.
		For 32-bit primary PCI Bus:
		• Pull up through individual external resistors
		(see Note 2 and Note 3).
P_FRAME#		Connect to FRAME# of the primary PCI bus.
P_DEVSEL#		Connect to DEVSEL# of the primary PCI bus.
P_IRDY#		Connect to IRDY# of the primary PCI bus.
P_TRDY#		Connect to TRDY# of the primary PCI bus.
P_STOP#		Connect to STOP# of the primary PCI bus.

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.

Intel® 31154 133 MHz PCI Bridge Design Guide Design Guide 19