Intel Pentium M Processor with 2-MB L2 Cache and 533-MHz Front Side Bus Datasheet

Datasheet 11
Low Power Features
2 Low Power Features
2.1 Clock Control and Low Power States
The Pentium M Processor supports the AutoHALT, Stop Grant, Sleep, Deep Sleep, and Deeper
Sleep states for optimal power management. See Figure 2-1 for a visual representation of the
processor low-power states.
2.1.1 Normal State
This is the normal operating state for the processor.
2.1.2 AutoHALT Powerdown State
AutoHALT is a low-power state entered when the processor executes the HALT instruction. The
processor will transition to the Normal state upon the occurrence of SMI#, INIT#, LINT[1:0]
(NMI, INTR), or FSB interrupt message. RESET# will cause the processor to immediately
initialize itself.
A system management interrupt (SMI) handler will return execution to either Normal state or the
AutoHALT Powerdown state. See the Intel Architecture Software Developer's Manual, Volume III:
System Programmer's guide for more information.
The system can generate a STPCLK# while the processor is in the AutoHALT Powerdown state.
When the system deasserts the STPCLK# interrupt, the processor will return execution to the
HALT state.
While in AutoHALT Powerdown state, the processor will process bus snoops and interrupts.
Figure 2-1. Clock Control States
snoop
occurs
Stop
Grant
Normal Sleep
HALT/
Grant
Snoop
Auto Halt
Deep
Sleep
STPCLK# asserted
SLP# asserted
SLP# de-asserted
STPCLK# de-asserted
snoop
serviced
HLT
instruction
snoop
serviced
snoop
occurs
DPSLP#
de-asserted
DPSLP#
asserted
STPCLK#
asserted
STPCLK#
de-asserted
halt
break
V0001-04
core voltage raised
core voltage lowered
Halt break - A20M#, INIT#, INTR, NMI, PREQ#, RESET#, SMI#, or APIC interrupt
Deeper
Sleep