Datasheet

Signal Descriptions
R
48 Datasheet
3.7 Voltage References, PLL Power
Table 19. Voltage References, PLL Power
Signal Name Type Description
Host Processor
HXRCOMP Analog Host RCOMP: Used to calibrate the Host AGTL+ I/O buffers.
HYRCOMP Analog Host RCOMP: Used to calibrate the Host AGTL+ I/O buffers.
HXSWING Analog Host Voltage Swing (RCOMP reference voltage): These signals provide a reference
voltage used by the FSB RCOMP circuit.
HYSWING Analog Host Voltage Swing (RCOMP reference voltage): These signals provide a reference
voltage used by the FSB RCOMP circuit.
HDVREF[2:0] Ref Analog Host Data (input buffer) VREF: Reference voltage input for the data signals of the
Host AGTL+ Interface. Input buffer differential amplifier to determine a high versus low
input voltage.
HAVREF Ref Analog Host Address (input buffer) VREF: Reference voltage input for the address signals
of the Host AGTL+ Interface. This signal is connected to the input buffer differential
amplifier to determine a high versus low input voltage.
HCCVREF Ref Analog Host Common Clock (Command input buffer) VREF: Reference voltage input for
the common clock signals of the Host AGTL+ Interface. This signal is connected to the
input buffer differential amplifier to determine a high versus low input voltage.
VTTLF Power FSB Power Supply: VTTLF is the low frequency connection from the board. This
signal is the primary connection of power for GMCH.
VTTHF Power FSB Power Supply: VTTHF is the high frequency supply. It is for direct connection
from an internal package plane to a capacitor placed immediately adjacent to the
GMCH.
NOTE: Not to be connected to power rail.
System Memory
SMRCOMP Analog System Memory RCOMP: This signal is used to calibrate the memory I/O buffers.
SMVREF_0 Ref Analog Memory Reference Voltage (Input buffer VREF):Reference voltage input for Memory
Interface.
Input buffer differential amplifier to determine a high versus low input voltage.
SMVSWINGH Ref Analog RCOMP reference voltage: This is connected to the RCOMP buffer differential
amplifier and is used to calibrate the I/O buffers.
SMVSWINGL Ref Analog RCOMP reference voltage: This is connected to the RCOMP buffer differential
amplifier and is used to calibrate the I/O buffers.
VCCSM Power Power supply for Memory I/O.
VCCQSM Power Power supply for system memory clock buffers.
VCCASM Power Power supply for system memory logic running at the core voltage (isolated supply, not
connected to the core).
Hub Interface
HLRCOMP Analog Hub Interface RCOMP: This signal is connected to a reference resistor in order to
calibrate the buffers.