RJ80535 Intel, RJ80535 Datasheet - Page 73

• Manufacturer Part Number: RJ80535
• Description: Pentium M Processor
• Manufacturer: Intel

Intel
®
Pentium
Note: PROCHOT# will not be asserted when the processor is in the Stop-Grant, Sleep, Deep Sleep, and
®
When Intel Thermal Monitor 1 is enabled, and a high temperature situation exists, the clocks will
be modulated by alternately turning the clocks off and on at a 50% duty cycle. Cycle times are
processor speed dependent and will decrease linearly as processor core frequencies increase. After
the temperature has returned to a non-critical level, modulation ceases and the TCC goes inactive.
A small amount of hysteresis has been included to prevent rapid active/inactive transitions of the
TCC when the processor temperature is near the trip point. 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. Processor performance will be decreased by the same
amount as the duty cycle when the TCC is active, however, with a properly designed and
characterized thermal solution the TCC most likely will never be activated, or will be activated
only briefly during the most power intensive applications.
The TCC may also be activated using On-Demand mode. If bit 4 of the ACPI Intel 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 Intel Thermal Monitor
Control Register. In Automatic mode, the duty cycle is fixed at 50% on, 50% off, 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 can be used at the same time Automatic mode is enabled,
however, if the system tries to enable the TCC via On-Demand mode at the same time Automatic
mode is enabled and a high temperature condition exists, Automatic mode will take precedence.
An external signal, PROCHOT# (processor hot) is asserted when the processor detects that its
temperature is above the thermal trip point. Bus snooping and interrupt latching are also active
while the TCC is active.
Deeper Sleep low power states (internal clocks stopped), hence the thermal diode reading must be
used as a safeguard to maintain the processor junction temperature within the 100 °C (maximum)
specification. If the platform thermal solution is not able to maintain the processor junction
temperature within the maximum specification, the system must initiate an orderly shutdown to
prevent damage. If the processor enters one of the above low power states with PROCHOT#
already asserted, PROCHOT# will remain asserted until the processor exits the low power state
and the processor junction temperature drops below the thermal trip point.
If Automatic mode is disabled the processor will be operating out of specification. Whether the
automatic or On-Demand modes are enabled or not, in the event of a catastrophic cooling failure,
the processor will automatically shut down when the silicon has reached a temperature of
approximately 125 °C. At this point the system bus signal THERMTRIP# will go active.
THERMTRIP# activation is independent of processor activity and does not generate any bus
cycles. When THERMTRIP# is asserted, the processor core voltage must be shut down within the
time specified in
M Processor Datasheet
2.If the processor load-based Enhanced Intel SpeedStep technology transition target
frequency is
lower than the Intel Thermal Monitor 2 transition based target frequency, the processor will
transition to the processor load-based Enhanced Intel SpeedStep technology target
frequency point.
Chapter
3.
Thermal Specifications and Design Considerations
73