Mobile Intel Pentium 4 Processor with 533 MHz Front Side Bus

72 Mobile Intel
®
Pentium
®
4 Processor with 533 MHz System Bus Datasheet
Configuration and Low Power Features
6.2.2 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#, BINIT#, INIT#,
LINT[1:0] (NMI, INTR), or PSB interrupt message. RESET# will cause the processor to
immediately initialize itself.
The return from a System Management Interrupt (SMI) handler can be to either Normal mode 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 Power Down state, the processor will process FSB snoops and interrupts.
6.2.3 Stop-Grant State
When the STPCLK# pin is asserted, the Stop-Grant state of the processor is entered 20 bus clocks
after the response phase of the processor-issued Stop Grant Acknowledge special bus cycle.
Since the GTL+ signal pins receive power from the FSB, these pins should not be driven (allowing
the level to return to V
CC
) for minimum power drawn by the termination resistors in this state. In
addition, all other input pins on the FSB should be driven to the inactive state.
BINIT# will not be serviced while the processor is in Stop-Grant state. The event will be latched
and can be serviced by software upon exit from the Stop-Grant state.
Figure 16. 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
Deeper
Sleep
Halt break - A20M#, BINIT#, INIT#, INTR, NMI, PREQ#, RESET#, SMI#, or APIC interrupt