Toshiba Xeon 2.8GHz UPG3843W Manuale Utente

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For automatic mode, the duty cycle is factory configured and cannot be modified. Also, automatic
mode does not require any additional hardware, software drivers or interrupt handling routines.

The TCC may also be activated via On-Demand mode. If bit 4 of the ACPI Thermal Monitor
Control Register is written to a “1” the TCC will be activated immediately, independent of the
processor temperature. When using On-Demand mode to activate the TCC, the duty cycle of the
clock modulation is programmable via bits 3:1 of the same ACPI Thermal Monitor Control
Register. In automatic mode, the duty cycle is fixed anywhere within a range of 30% to 50%;
however in On-Demand mode, the duty cycle can be programmed from 12.5% on/ 87.5% off, to
87.5% on/12.5% off in 12.5% increments. On-Demand mode may be used at the same time
Automatic mode is enabled, however, if TCC is enabled via On-Demand mode at the same time
automatic mode is enabled AND a high temperature condition exists, the fixed duty cycle of the
automatic mode will override the duty cycle selected by the On-Demand mode.

An external signal, PROCHOT# (processor hot) is asserted at any time the TCC is active (either in
Automatic or On-Demand mode). Bus snooping and interrupt latching are also active while the
TCC is active. The temperature at which the thermal control circuit activates is not user
configurable and is not software visible. In an MP system, Thermal Monitor must be configured
identically for each processor within the system.

Besides the thermal sensor and thermal control circuit, the Thermal Monitor feature also includes
one ACPI register, one performance counter register, three model specific registers (MSR), and one
I/O pin (PROCHOT#). All are available to monitor and control the state of the Thermal Monitor
feature. Thermal Monitor can be configured to generate an interrupt upon the assertion or de-
assertion of PROCHOT# (i.e. upon the activation/deactivation of TCC). Refer to Volume 3 of the
IA32 Intel Architecture Software Developer’s for specific register and programming details.

If automatic mode is disabled the processor will be operating out of specification and cannot be
guaranteed to provide reliable results. Regardless of enabling of the automatic or On-Demand
modes, in the event of a catastrophic cooling failure, the processor will automatically shut down
when the silicon has reached a temperature of approximately 135 °C. At this point the front side
bus signal THERMTRIP# will go active and stay active until the processor has cooled down and
RESET# has been initiated. THERMTRIP# activation is independent of processor activity and
does not generate any bus cycles.If THERMTRIP# is asserted, processor core voltage (V

CC

) must

be removed within the timeframe defined in 

The processor incorporates an on-die thermal diode. A thermal sensor located on the processor may
be used to monitor the die temperature of the processor for thermal management/long term die
temperature change purposes. This thermal diode is separate from the Thermal Monitor’s thermal
sensor and cannot be used to predict the behavior of the Thermal Monitor. See 

 for

details.

The processor includes an SMBus interface which allows access to a memory component with two
sections (referred to as the Processor Information ROM and the Scratch EEPROM) and a thermal
sensor on the substrate. The SMBus thermal sensor may be used to read the thermal diode
mentioned in 

. These devices and their features are described below. See 

for the physical location of these devices.