Thrmdp And Thrmdn; Additional Routing And Placement Considerations; Figure 26. Routing For Thrmdp And Thrmdn - Intel 815EG Design Manual

System Bus Design Guidelines
5.2.3

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 crosstalk. The traces should
be routed close together to reduce loop area and inductance.

Figure 26. Routing for THRMDP and THRMDN

NOTES:
1.
2.
5.2.4

Additional Routing and Placement Considerations

• Distribute VTT with a wide trace. An 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 1.5 V ± 3% for static conditions, and 1.5 V ± 9% for worst-case
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 1.25 V ± 3% for static conditions, and 1.25 V ± 9% for
worst-case transient conditions.
• Place resistor divider pairs for VREF generation at the GMCH component. VREF also is
delivered to the processor.
56
Signal Y
THRMDP
THRMDN
Signal Z
Route these traces parallel and equalize lengths within ± 0.5 inch.
Route THRMDP and THRMDN on the same layer.
1 — Maximize (min. – 20 mils)
2 — Minimize
1 — Maximize (min. – 20 mils)
bus_routing_thrmdp-thrmdn
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Intel 815EG Chipset Platform Design Guide
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