Datasheet
11
Low Power Features
2
Low Power Features
2.1
Clock Control and Low Power States
The Pentium M processor supports the AutoHALT Power-Down, Stop Grant, Sleep, Deep Sleep,
and Deeper Sleep states for optimal power management. See
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 Power-Down State
AutoHALT Power-Down 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 Power-Down state. See the
IA-32 Intel
®
Architecture Software Developer's Manual,
Volume 3: System Programmer's Guide
for more information.
Figure 2-1. Clock Control States
snoop
occurs
Stop
Grant
Normal
Sleep
HALT/
Grant
Snoop
Auto Halt
Deep
Sleep
STPCLK# asserted
SLP# asserted
SLP# deasserted
STPCLK# deasserted
snoop
serviced
HLT
instruction
snoop
serviced
snoop
occurs
DPSLP#
de-asserted
DPSLP#
asserted
STPCLK#
asserted
STPCLK#
deasserted
halt
break
V0001-04
core voltage raised
core voltage lowered
Halt break - A20M#, INIT#, INTR, NMI, PREQ#, RESET#, SMI#, or APIC interrupt
Deeper
Sleep