Intel Xeon User Manual

Intel
®
82870P2 (P64H2)
110 Design Guide
8.2.6.8 SMBus Address Considerations
In Dual Slot Parallel mode, the SMBus address strap pins in Table 8-7 are muxed as Hot Plug
control signals HxRESETA# and HxBUSENB#. Therefore, it is recommended that the following
technique be used for determining an SMBus address. Pull the PA_GNT5 (RESETA#) signals to
ground through a 100
kΩ ± 5% resistor. This keeps the reset signal active until the P64H2 is ready
for it to become deasserted. Pull the PA_ GNT4 (BUSENB#) signals to 3.3 V through a
10
kΩ ± 5% resistor. The P64H2 will be able to drive this signal to ground when the signal must be
asserted.
Keep in mind that this limits the range of addresses you can achieve. Using this technique, the
address is fixed if operating in dual slot mode on both controllers.
Figure 8-13. Dual Slot Parallel SMBus Circuit
Slot 1
10 kΩ
3.3V
HX_BUSENB#
HX_RESETA#
HX_RESETB#
HX_BUSENA#
Switch
Switch
Slot 2
100 kΩ
Intel
®
P64H2

Intel Xeon Specifications

General

Brand	Intel
Model	Xeon
Category	Processor
Language	English