Intel 820E manual Hub Interface Signal Routing Example

Intel® 820E Chipset

R

2.9.Hub Interface

The MCH and ICH2 ballout assignments have been optimized to simplify the hub interface routing between these devices. It is recommended that the hub interface signals be routed directly from the MCH to ICH2, with all signals referenced to VSS. Layer transition should be keep to a minimum. If a layer change is required, use only two vias per net and keep all data signals and associated strobe signals on the same layer. The hub interface is broken into two signal groups: data signals and strobe signals. These groups are:

•Data signal

HL[10:0]

•Strobe signals

HL_STB

HL_STB#

Note: HL_STB/HL_STB# is a differential strobe pair.

For the 8-bit hub interface, HL[7:0] are associated with HL_STB and HL_STB#.

No pull-ups or pull-downs are required on the hub interface.

Each signal must be routed so as to meet the guidelines documented for the signal group to which it belongs.

Figure 42. Hub Interface Signal Routing Example

ICH2

HL_STB

HL_STB#

HL[10:0]

MCH

CLK66

CLK66

CLK synthesizer

hub_sig_route

74 Design Guide