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Signal Definitions
72
Dual-Core Intel® Xeon® Processor 7100 Series Datasheet
§
V
CC_CACHE_SENSE
V
SS_CACHE_SENSE
O
V
CC_CACHE_SENSE
 and V
SS_CACHE_SENSE
 provide isolated, low impedance 
connections to the processor cache voltage (V
CACHE
) and ground (V
SS
). They 
can be used to sense or measure voltage or ground near the silicon with little 
noise.
V
CCIOPLL
I
V
CCIOPLL
 provides isolated power for digital portion of the internal PLL’s. Follow 
the guidelines for V
CCA
, and refer to the appropriate platform design guide for 
complete implementation details.
V
CCPLL
I
The on-die PLL filter solution will not be implemented on this platform. The 
V
CCPLL
 input should be left unconnected.
V
CCSENSE
V
SSSENSE
O
V
CCSENSE
 and V
SSSENSE
 provide isolated, low impedance connections to the 
processor core voltage (V
CC
) and ground (V
SS
). These signals must be 
connected to the voltage regulator feedback signals, which ensure the output 
voltage (i.e. processor voltage) remains within specification. Please see the 
applicable platform design guide for implementation details.
VID[5:0]
O
VID[5:0] (Voltage ID) pins are used to support automatic selection of V
CC
These are open drain signals that are driven by the processor and must be 
pulled to no more than 3.3 V (+5% tolerance) with a resistor. Conversely, the 
V
CC
 VR output must be disabled prior to the voltage supply for these pins 
becoming invalid. The VID pins are needed to support processor voltage 
specification variations. See 
 for definitions of these pins. The V
CC
 VR 
must supply the voltage that is requested by these pins, or disable itself.
VIDPWRGD
I
The processor requires this input to determine that the supply voltage for 
BSEL[1:0], VID[5:0], and CVID[3:0] is stable and within specification.
V
SS
I
V
SS
 is the ground plane for the Dual-Core Intel Xeon processor 7100 series.
V
SSA
I
V
SSA
 provides an isolated, internal ground for internal PLL’s. Do not connect 
directly to ground. This pin is to be connected to V
CCA
 and V
CCIOPLL
 through a 
discrete filter circuit.
V
TT
I
V
TT
 is the front side bus termination voltage.
VTTEN
O
VTTEN can be used as an output enable for the V
TT
 regulator. VTTEN is used as 
an electrical key to prevent processors with mechanically-equivalent pinouts 
from accidentally booting in a Dual-Core Intel Xeon processor 7100 series 
platform. Since VTTEN is an open circuit on the processor package, VTTEN 
must be pulled up on the motherboard. Refer to the appropriate platform 
design guide for implementation details.
Table 5-1.
Signal Definitions (Sheet 8 of 8)
Name
Type
Description