RG82855GMESL72L Datasheet, PDF (48/213 Pages) Intel Corporation – Intel® 855GM/855GME Chipset Graphics and Memory Controller Hub (GMCH)

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