Thrmdp And Thrmdn; Additional Routing And Placement Considerations; Figure 21. Routing For Thrmdp And Thrmdn - Intel 815 Design Manual

System Bus Design Guidelines
5.2.1.2

THRMDP and THRMDN

These traces (THRMDP and THRMDN) route the processor's thermal diode connections. The
thermal diode operates at very low currents and may be susceptible to cross-talk. The traces should
be routed close together to reduce loop area and inductance.

Figure 21. Routing for THRMDP and THRMDN

THRMDP
THRMDN
NOTES:
1. Route these traces parallel and equalize lengths within 0.5 inch.
2. Route THRMDP and THRMDN on the same layer.
5.2.1.3

Additional Routing and Placement Considerations

Distribute VTT with a wide trace. A 0.050 inch minimum trace is recommended to minimize
DC losses. Route the VTT trace to all components on the host bus. Be sure to include
decoupling capacitors.
The VTT voltage should be 1.5V
transient conditions when the Pentium III processor (CPUID=068xh) or Celeron processor
(CPUID=068xh) is present in the socket. If a future 0.13 micron socket 370 processor is being
used, the VTT voltage should then be 1.25V
worst-case transient conditions.
Place resistor divider pairs for VREF generation at the GMCH component. VREF also is
delivered to the processor.
50
Signal Y
Signal Z
1 — Maximize (min. – 20 mils)
2 — Minimize
1 — Maximize (min. – 20 mils)
bus_routing_thrmdp-thrmdn
3% for static conditions, and 1.5V
3% for static conditions, and 1.25V
®
Intel 815 Chipset Platform Design Guide
R
9% for worst-case
9% for