Datasheet 73
Land Listing and Signal Descriptions
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VID[5:0] Output
VID[5:0] (Voltage ID) signals are used to support automatic selection of power
supply voltages (V
CC
). These are open drain signals that are driven by the
processor and must be pulled up on the motherboard. Refer to the Voltage
Regulator-Down (VRD) 10.1 Design Guide for Desktop Socket 775 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 2-2
for definitions of these signals. The VR must supply the voltage that is
requested by the signals, or disable itself.
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) 10.1 Design Guide for Desktop
Socket 775.
VTT Miscellaneous voltage supply.
VTT_OUT_LEFT
VTT_OUT_RIGHT
Output
The VTT_OUT_LEFT and VTT_OUT_RIGHT signals are included to provide a
voltage supply for some signals that require termination to V
TT
on the
motherboard.
For future processor compatibility some signals are required to be pulled up to
VTT_OUT_LEFT or VTT_OUT_RIGHT. Refer to the following table for the
signals that should be pulled up to VTT_OUT_LEFT and VTT_OUT_RIGHT.
VTT_SEL Output
The VTT_SEL signal is used to select the correct V
TT
voltage level for the
processor.
VTTPWRGD Input
The processor requires this input to determine that the V
TT
voltages are stable
and within specification.
Table 4-3. Signal Description (Sheet 8 of 8)
Name Type Description
Pull-up Signal Signals to be Pulled Up
VTT_OUT_RIGHT
VTT_PWRGOOD, VID[5:0], GTLREF, TMS, TDI,
TDO, BPM[5:0], other VRD components
VTT_OUT_LEFT
RESET#, BR0#, PWRGOOD, TESTHI1, TESTHI8,
TESTHI9, TESTHI10, TESTHI11, TESTHI12
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