Low Power Features
Since the AGTL+ signal pins receive power from the FSB, these pins should not be
driven (allowing the level to return to VCCP) 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.
RESET# will cause the processor to immediately initialize itself, but the processor will
stay in Stop-Grant state. A transition back to the Normal state will occur with the
deassertion of the STPCLK# signal. When re-entering the Stop-Grant state from the
Sleep state, STPCLK# should be deasserted ten or more bus clocks after the
deassertion of SLP#.
A transition to the HALT/Grant Snoop state will occur when the processor detects a
snoop on the FSB (see Section 2.1.4). A transition to the Sleep state (see
Section 2.1.5) will occur with the assertion of the SLP# signal.
While in the Stop-Grant state, SMI#, INIT# and LINT[1:0] will be latched by the
processor, and only serviced when the processor returns to the Normal State. Only one
occurrence of each event will be recognized upon return to the Normal state.
While in Stop-Grant state, the processor will process snoops on the FSB, and it will
latch interrupts delivered on the FSB.
The PBE# signal can be driven when the processor is in Stop-Grant state. PBE# will be
asserted if there is any pending interrupt latched within the processor. Pending
interrupts that are blocked by the EFLAGS.IF bit being clear will still cause assertion of
PBE#. Assertion of PBE# indicates to system logic that it should return the processor to
the Normal state.
2.1.4
2.1.5
HALT/Grant Snoop State
The processor will respond to snoop or interrupt transactions on the FSB while in Stop-
Grant state or in AutoHALT Power-Down state. During a snoop or interrupt transaction,
the processor enters the HALT/Grant Snoop state. The processor will stay in this state
until the snoop on the FSB has been serviced (whether by the processor or another
agent on the FSB) or the interrupt has been latched. After the snoop is serviced or the
interrupt is latched, the processor will return to the Stop-Grant state or AutoHALT
Power-Down state, as appropriate.
Sleep State
A low power state in which the processor maintains its context, maintains the phase-
locked loop (PLL), and has stopped all internal clocks. The Sleep state can be entered
only from Stop-Grant state. Once in the Stop-Grant state, the processor will enter the
Sleep state upon the assertion of the SLP# signal. The SLP# pin should only be
asserted when the processor is in the Stop Grant state. SLP# assertions while the
processor is not in the Stop-Grant state is out of specification and may result in
unapproved operation.
Snoop events that occur while in Sleep State or during a transition into or out of Sleep
state will cause unpredictable behavior.
In the Sleep state, the processor is incapable of responding to snoop transactions or
latching interrupt signals. No transitions or assertions of signals (with the exception of
SLP#, DPSLP# or RESET#) are allowed on the FSB while the processor is in Sleep
state. Any transition on an input signal before the processor has returned to Stop-Grant
state will result in unpredictable behavior.
If RESET# is driven active while the processor is in the Sleep state, and held active as
specified in the RESET# pin specification, then the processor will reset itself, ignoring
the transition through Stop-Grant State. If RESET# is driven active while the processor
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Datasheet
INTEL [ INTEL ]
