251308-008 Datasheet, PDF (88/91 Pages) Intel Corporation – Mobile Intel Celeron Processor on .13 Micron Process and in FCPGA Package

Configuration and Low Power Features
7.2.2 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 Powerdown state, the processor will process bus snoops.
Figure 33. Clock Control States
STPCLK# asserted
Normal _{STPCLK# de-asserted}
Stop
Grant
halt
break _HLT
instruction
STPCLK#
asserted
STPCLK#
snoop
serviced
snoop
occurs
de-asserted
SLP# asserted
Sleep
SLP# de-asserted
DPSLP#
de-asserted
DPSLP#
asserted
Auto Halt
snoop
occurs
snoop
serviced
HALT/
Grant
Snoop
Deep
Sleep
V0001-04
Halt break - A20M#, BINIT#, INIT#, INTR, NMI, PREQ#, RESET#, SMI#, or APIC interrupt
7.2.3
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 AGTL+ 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.
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Datasheet