System Considerations
CP605
Page 6 - 4
© 2004 Kontron Modular Computers GmbH
ID 25095, Rev. 07
2509
5.07.UG.VC.041005/14244
8
6.1.1.2
CPU External Thermal Supervision
This function can be enabled and disabled in the BIOS, whereby the default value is: enabled.
There are two independent and isolated thermal sensors in the Pentium 4 processor. One is
the on-die thermal diode. The other is the temperature sensor used for the Thermal Monitor
and for Thermtrip. The measured temperature of both sensors can vary significantly, whereby
the temperature of the external measured on-die sensors is always lower.
When the external thermal control circuit has been enabled and a high temperature situation
occurs, the front panel “TH” LED will be switched on and the external Stopclock signal of the
processor will be modulated by alternately turning the clocks off and on at a duty cycle specified
in the BIOS (12.5% - 75%) and the processor power dissipation will be reduced.
The thermal control circuit does not automatically go inactive once the temperature goes below
the selected external thermal supervision point. Explicit software action is necessary to switch
back to normal mode.
6.1.1.3
CPU Emergency Thermal Supervision
This function can not be enabled and disabled in the BIOS. It is always enabled to ensure that
the processor is protected in any event.
Assertion of “Thermtrip” (Thermal Trip) indicates that the processor junction temperature has
reached a level beyond which permanent silicon damage may occur. Measurement of the tem-
perature is accomplished through an internal thermal sensor which is configured to trip at ap-
proximately 135°C. Upon assertion of Thermtrip, the processor will shut off its internal clocks
(thus halting program execution) in an attempt to reduce the processor junction temperature.
Once activated, Thermtrip remains latched until the CP605 undergoes a cold restart is per-
formed (all power off and then on again).
Note ...
The duty cycle and the external thermal supervision point can be configured in
the BIOS. The default external thermal supervision point is 85 °C.
Note ...
Upon assertion of “Thermtrip”, the front panel overtemperature LED flashes at
regular intervals.
