
Intel XeonTM Processor MP
84
Datasheet
PROCHOT#
O
PROCHOT# (processor hot) indicates that the processor Thermal Control Circuit (TCC) has
been activated. Under most conditions, PROCHOT# will go active when the processor’s
thermal sensor detects that the processor has reached its maximum safe operating
PWRGOOD
I
PWRGOOD (Power Good) is an input. The processor requires this signal to be a clean
indication that the clocks and power supplies are stable and within their specifications.
“Clean” implies that the signal will remain low (capable of sinking leakage current),
without glitches, from the time that the power supplies are turned on until they come within
specification. The signal must then transition monotonically to a high state.
Figure 10illustrates the relationship of PWRGOOD to the RESET# signal. PWRGOOD can be driven
inactive at any time, but clocks and power must again be stable before a subsequent rising
edge of PWRGOOD. It must also meet the minimum pulse width specification in
Table 15,andbe followedbya 1ms RESET# pulse.
The PWRGOOD signal must be supplied to the processor; it is used to protect internal
circuits against voltage sequencing issues. It should be driven high throughout boundary
scan operation.
REQ[4:0]#
I/O
REQ[4:0]# (Request Command) must connect the appropriate pins of all processor system
bus agents. They are asserted by the current bus owner to define the currently active
transaction type. These signals are source synchronous to ADSTB[1:0]#. Refer to the
AP[1:0]# signal description for details on parity checking of these signals.
RESET#
I
Asserting the RESET# signal resets all processors to known states and invalidates their
internal caches without writing back any of their contents. For a power-on Reset, RESET#
must stay active for at least one millisecond after VCC and BCLK have reached their proper
specifications. On observing active RESET#, all system bus agents will deassert their
outputs within two clocks. RESET# must not be kept asserted for more than 10ms.
A number of bus signals are sampled at the active-to-inactive transition of RESET# for
power-on configuration. These configuration options are described in the
Section 7.1.This signal does not have on-die termination and must be terminated at the end agent.
RS[2:0]#
I
RS[2:0]# (Response Status) are driven by the response agent (the agent responsible for
completion of the current transaction), and must connect the appropriate pins of all
processor system bus agents.
RSP#
I
RSP# (Response Parity) is driven by the response agent (the agent responsible for
completion of the current transaction) during assertion of RS[2:0]#, the signals for which
RSP# provides parity protection. It must connect to the appropriate pins of all processor
system bus agents.
A correct parity signal is high if an even number of covered signals are low and low if an
odd number of covered signals are low. While RS[2:0]# = 000, RSP# is also high, since this
indicates it is not being driven by any agent guaranteeing correct parity.
SKTOCC#
O
SKTOCC# (Socket occupied) will be pulled to ground by the processor to indicate that the
processor is present.
SLP#
I
SLP# (Sleep), when asserted in Stop-Grant state, causes processors to enter the Sleep state.
During Sleep state, the processor stops providing internal clock signals to all units, leaving
only the Phase-Locked Loop (PLL) still operating. Processors in this state will not
recognize snoops or interrupts. The processor will recognize only assertion of the RESET#
signal or deassertion of SLP#. If SLP# is deasserted, the processor exits Sleep state and
returns to Stop-Grant state, restarting its internal clock signals to the bus and processor core
units.
SM_ALERT#
O
SM_ALERT# is an asynchronous interrupt line associated with the SMBus Thermal Sensor
device. It is an open-drain output and the processor includes a 10k
pull-up resistor to
SM_VCC for this signal. For more information on the usage of the SM_ALERT# pin, see
SM_CLK
I/O
The SM_CLK (SMBus Clock) signal is an input clock to the system management logic
which is required for operation of the system management features of the Intel Xeon
processor. This clock is driven by the SMBus controller and is asynchronous to other clocks
in the processor.The processor includes a 10k
pull-up resistor to SM_V
CC for this signal.
Table 33. Signal Definitions (Page 6 of 8)
Name
Type
Description