Intel
®
Pentium
®
III Processor with 512KB L2 Cache Dual Processor Platform Design Guide
6-1
Thermals
6
The Intel
®
Pentium
®
III Processor with 512KB L2 Cache requires a robust thermal solution for proper
operation. To provide detail descriptions and example solutions for effective thermal management, a
separate document has been created. Please see the Intel
®
Pentium
®
III Processor with 512KB L2
Cache Datasheet and Intel
®
Pentium
®
III Processor in the FC-PGA2 Package Thermal Design
Guidelines for more information.
6.1
THERMTRIP# Requirements
In the event the processor drives the THERMTRIP# signal active during valid operation, both the Vcc
and Vtt supplies to the processor must be powered off to prevent thermal runaway of the processor. Valid
operation refers to the operating conditions where the THERMTRIP# signal is guaranteed valid. The time
required from THERMTRIP# assertion to Vcc rail at 1/2 nominal is 5 seconds and THERMTRIP#
asserted to Vtt rail at 1/2 nominal is 5 seconds.
6.2
THERMTRIP# Erratum
Intel has identified an issue with THERMTRIP# which may incorrectly assert during de-assertion of
RESET# at nominal operating temperatures in Intel
®
Pentium
®
III Processors with 512KB L2 Cache
(CPUID 06B1h). The assertion of THERMTRIP# will cause the processor to shut down internally and
stop execution. This issue can lead to intermittent system power-on boot failures.
To prevent the risk of power-on boot failures a platform workaround is required. The system must
provide a rising edge on the TCK signal during the power-on sequence that meets all of the following
requirements:
•
Edge occurs after Vcc
CORE
is valid and stable
•
Edge occurs before or at the de-assertion of RESET#
•
Edge occurs after all Vref input signals are at valid voltage levels
•
TCK input meets the Vih
min
and Vih
max
requirements of the Intel
®
Pentium
®
III Processor with
512KB L2 Cache Datasheet.
Specific workaround implementations may be platform specific. The following example has been tested
as an acceptable workaround implementation.
Table 6-1. THERMTRIP# Timing Requirements
Power Rail
Power Target
Time Required for Power
Drop
Vcc
1/2 Nominal Vcc
5.0 seconds
Vtt
1/2 Nominal Vtt
5.0 seconds
