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Clock Interface
© 2009 Advanced Micro Devices, Inc.
45732 AMD 780E Databook 3.10
Proprietary
3-7
3.6
Clock Interface
3.7
CRT Interface
Table 3-7 Clock Interface
Pin Name
Type
Power
Domain
Ground
Domain
Integrated
Termination Functional Description
HT_REFCLKP,
HT_REFCLKN
I
VDDA18H
TPLL
VSSAHT
–
HyperTransport™ 100MHz reference clock differential pair input from
external clock source
GFX_REFCLKP,
GFX_REFCLKN
I/O
VDDPCIE VSSAPCIE
50
between
complements
Clock Differential Pair for external graphics. Input from the external
clock generator, as a reference clock for external graphics.
GPPSB_REFCLKP,
GPPSB_REFCLKN
I
VDDPCIE VSSAPCIE
50
between
complements
Clock Differential Pair for Southbridge and general purpose PCI-E
devices. Input from the external clock generator, as a reference clock
for A-Link II and general purpose PCI-E.
GPP_REFCLKP,
GPP_REFCLKN
O
VDDPCIE VSSAPCIE
50
between
complements
Clock Differential Pair for general purpose PCI-E devices.
Not used.
Can be left unconnected, or connected to the external clock generator
for maintaining system compatibility with the RX780 or RD780.
REFCLK_P,
REFCLK_N
I
VDD33
VSS
–
Reference clock input for the RS780E. REFCLK_P is a single-ended,
14.31818MHz input from the external clock generator; input swing
should be 1.1V. Connect REFCLK_N to VREF (0.55V) on the
motherboard.
Table 3-8 CRT Interface
Pin Name
Type
Power
Domain
Ground
Domain
Integrated
Termination Functional Description
RED
A-O
AVDD
–
–
Red for CRT monitor output
GREEN
A-O
AVDD
–
–
Green for CRT monitor output
BLUE
A-O
AVDD
–
–
Blue for CRT monitor output
DAC_HSYNC
A-O
VDD33
VSS
50k
programmable:
PU/PD/none
Display Horizontal Sync
DAC_VSYNC
A-O
VDD33
VSS
50k
programmable:
PU/PD/none
Display Vertical Sync
DAC_RSET
Other
N/A
AVSSQ
–
DAC internal reference to set full scale DAC current through 1%
resistor to AVSSQ
DAC_SDA
I/O
VDD33
VSS
50k
programmable:
PU/PD/none
I
2
C™ data for display (to video monitor). The signal is 5V-tolerant.
DAC_SCL
I/O
VDD33
VSS
50k
programmable:
PU/PD/none
I
2
C clock for display (to video monitor). The signal is 5V-tolerant.