82845PE Datasheet, PDF (34/176 Pages) Intel Corporation – 82845GE Graphics and Memory Controller Hub (GMCH) and 82845PE Memory Controller Hub (MCH)

Signal Description
2.7
2.8
34
Clocks, Reset, and Miscellaneous Signals
Signal Name
HCLKP
HCLKN
GCLKIN
DREFCLK
(82845GE only)
RSTIN#
PWROK
TESTIN#
Type
I
CMOS
I
LVTTL
I
LVTTL
I
LVTTL
I
3.3 V
GPIO
I
1.5 V
CMOS
Description
Differential Host Clock In: These pins receive a low voltage differential host
clock from the external clock synthesizer.
66 MHz Clock In: This pin receives a 66 MHz clock from the clock synthesizer.
This clock is used by AGP and hub interface clock domains.
Display Clock Input: This pin provides a 48 MHz input clock to the Display PLL
that is used for 2D/Video/Flat Panel and DAC.
Reset In: When asserted, this signal asynchronously resets the (G)MCH logic.
This signal is connected to the PCIRST# output of the ICH4. All AGP/PCI output
and bi-directional signals will also tri-state compliant to PCI Local Bus
Specification, Revision 2.0 and PCI Local Bus Specification, Revision 2.1.
Power OK: When asserted, PWROK is an indication to the (G)MCH that the
core power and GCLKIN have been stable for at least 10 µs.
Test Input: This pin is used for manufacturing and board lever test purposes.
RCOMP, VREF, VSWING Signals
Signal Name
HDVREF_[2:0]
HA_VREF
HCC_VREF
HX_RCOMP
HY_RCOMP
HX_SWING
HY_SWING
SM_VREF
SMXRCOMP
SMYRCOMP
AGP_VREF
AGP_RCOMP
HI_VREF
HI_RCOMP
HI_SWING
Type
I
I
I
I/O
CMOS
I
I
I/O
CMOS
I
I/O
CMOS
I
I/O
CMOS
I
Description
Host Data Reference Voltage: Reference voltage input for the data signals of the
Host AGTL+ interface.
Host Address Reference Voltage: Reference voltage input for the address
signals of the Host AGTL+ interface.
Host Common Clock Reference Voltage: Reference voltage input for the
common clock signals of the Host AGTL+ interface.
Host RCOMP: These pins are used to calibrate the Host AGTL+ I/O buffers.
Host Voltage Swing: These pins provide a reference voltage used by the PSB
RCOMP circuit. HX_SWING is used for the signals handled by HX_RCOMP, and
HY_SWING is used for the signals handled by HY_RCOMP.
Memory Reference Voltage: Reference voltage input for DQ, DQS &
SRCVEN_IN#.
Memory RCOMP: These pins are used to calibrate the memory I/O buffers.
AGP Reference: The reference voltage for the AGP/DVO I/O buffers is 0.75 V.
Compensation for AGP: This signal is used to calibrate the AGP/DVO buffers.
This signal should be connected to ground through a 40 Ω pull-down resistor.
HI Reference: Reference voltage input for the hub interface.
Compensation for HI: This signal is used to calibrate the hub interface I/O
buffers. This signal should be connected to 1.5 V through a 68.1 Ω 1% pull-up
resistor
HI Voltage Swing: This signal provides a reference voltage used by the
HI_RCOMP circuit.
Intel^® 82845GE/82845PE Datasheet