Land Listing and Signal Descriptions
Dual-Core Intel® Xeon® Processor 3000 Series Datasheet 73
THERMTRIP# Output In the event of a catastrophic cooling failure, the processor will
automatically shut down when the silicon has reached a temperature
approximately 20 °C above the maximum T
C
. Assertion of
THERMTRIP# (Thermal Trip) indicates the processor junction
temperature has reached a level beyond where permanent silicon
damage may occur. Upon assertion of THERMTRIP#, the processor will
shut off its internal clocks (thus, halting program execution) in an
attempt to reduce the processor junction temperature. To protect the
processor, its core voltage (V
CC
) must be removed following the
assertion of THERMTRIP#. Driving of the THERMTRIP# signal is
enabled within 10 μs of the assertion of PWRGOOD (provided V
TT
and
V
CC
are valid) and is disabled on de-assertion of PWRGOOD (if V
TT
or
V
CC
are not valid, THERMTRIP# may also be disabled). Once activated,
THERMTRIP# remains latched until PWRGOOD, V
TT
, or V
CC
is de-
asserted. While the de-assertion of the PWRGOOD, V
TT
, or V
CC
will de-
assert THERMTRIP#, if the processor’s junction temperature remains
at or above the trip level, THERMTRIP# will again be asserted within
10 μs of the assertion of PWRGOOD (provided V
TT
and V
CC
are valid).
TMS Input TMS (Test Mode Select) is a JTAG specification support signal used by
debug tools.
TRDY# Input TRDY# (Target Ready) is asserted by the target to indicate that it is
ready to receive a write or implicit writeback data transfer. TRDY#
must connect the appropriate pins/lands of all FSB agents.
TRST# Input TRST# (Test Reset) resets the Test Access Port (TAP) logic. TRST#
must be driven low during power on Reset.
VCC Input VCC are the power pins for the processor. The voltage supplied to
these pins is determined by the VID[7:0] pins.
VCCPLL Input VCCPLL provides isolated power for internal processor FSB PLLs.
VCC_SENSE Output VCC_SENSE is an isolated low impedance connection to processor core
power (V
CC
). It can be used to sense or measure voltage near the
silicon with little noise.
VCC_MB_
REGULATION
Output This land is provided as a voltage regulator feedback sense point for
V
CC
. It is connected internally in the processor package to the sense
point land U27 as described in the Voltage Regulator-Down (VRD)
11.0 Processor Power Delivery Design Guidelines For Desktop LGA775
Socket.
VID[7:0] Output VID[7:0] (Voltage ID) signals are used to support automatic selection
of power supply voltages (V
CC
). Refer to the Voltage Regulator-Down
(VRD) 11.0 Processor Power Delivery Design Guidelines For Desktop
LGA775 Socket for more information. The voltage supply for these
signals must be valid before the VR can supply V
CC
to the processor.
Conversely, the VR output must be disabled until the voltage supply
for the VID signals becomes valid. The VID signals are needed to
support the processor voltage specification variations. See Table 2-1
for definitions of these signals. The VR must supply the voltage that is
requested by the signals, or disable itself.
VID_SELECT Output This land is tied high on the processor package and is used by the VR
to choose the proper VID table. Refer to the Voltage Regulator-Down
(VRD) 11.0 Processor Power Delivery Design Guidelines For Desktop
LGA775 Socket for more information.
VRDSEL Input This input should be left as a no connect in order for the processor to
boot. The processor will not boot on legacy platforms where this land
is connected to V
SS
.
VSS Input VSS are the ground pins for the processor and should be connected to
the system ground plane.
VSSA Input VSSA is the isolated ground for internal PLLs.
VSS_SENSE Output VSS_SENSE is an isolated low impedance connection to processor core
V
SS
. It can be used to sense or measure ground near the silicon with
little noise.
VSS_MB_
REGULATION
Output This land is provided as a voltage regulator feedback sense point for
V
SS
. It is connected internally in the processor package to the sense
point land V27 as described in the Voltage Regulator-Down (VRD) 11.0
Processor Power Delivery Design Guidelines For Desktop LGA775
Socket.
Table 4-3. Signal Description (Sheet 6 of 7)
Name Type Description
