
RC7108
PRODUCT SPECIFICATION
4
Pin Descriptions
Pin Name
CPU0:1
Pin Number
44,43
Type
OUT
Pin Function Description
CPU Clock Outputs: These two CPU clocks are determined by the
4 select pins FS0:3
PCI BUS Clock Outputs: These 6 PCI clock outputs run
synchronously to the CPU.
I/O Dual Function PCI0 and FS0 pin: See table for frequency
selection. After power-on, this pin becomes a normal PCI clock.
I/O Dual Function PCI1 and FS1 pin: See table for frequency
selection. After power-on, this pin becomes a normal PCI clock.
3V66 Clock Outputs: These 2 outputs are fixed at 66MHz operating
from 3.3V.
REF Clock Output: This output provides a 14.318MHz high drive
clock .
I/O Dual Function REF0 and FREQ_APIC Pin: During power-up, if
the input is “0”, the IOAPIC output would operate at 16.67MHz. If the
input is latched “1”, the IOAPIC output would operate at 33.3MHz.
After power-on, this pin becomes a REF0 output. There is an
internal pull-up resistor on this pin.
I/O Dual Function IOAPIC and SEL_3V66 Pin: See table for
frequency selection.
SDRAM Clock Outputs: SDRAM0:7 clocks are determined by
FS0:FS3. SDRAM_F is a free-running clock which is not controlled
by the I
2
C.
I/O Dual Function 24MHz and FS2 pin: See table for frequency
selection. After power-on the pin becomes a normal 24MHz clock.
I/O Dual Function 48MHz and FS3 pin: See table for frequency
selection. After power-on the pin becomes a normal 48MHz clock.
Crystal Connection: An input connection for an external14.318MHz
crystal. If using an external reference, this pin must be left
unconnected.
Crystal Connection or External Reference Frequency Input:
Connect to either a 14.318MHz crystal or other reference signal.
Power-down Input pin: This pin shuts down the clock PLL bring all
clocks to a low state.
I
2
C Clock Pin: The I
2
C clock should be applied to this input as
described in the I
2
C section of this datasheet.
I
2
C Data Pin: Data should be presented to this input as described
by the I
2
C section of this datasheet. There is an internal pull-up
resistor on this pin.
3.3V Power Pins:
PCI2:7
13,15,16,
17,19,20
11
OUT
PCI0/FS0
OUT/IN
PCI1/FS1
12
OUT/IN
3V66-0:1
7,8
OUT
REF1
1
OUT
REF0/
FREQ_APIC
48
OUT/IN
IOAPIC/
SEL_3V66
SDRAM0:7
SDRAM_F
46
OUT/IN
40,39,38,36,
35,34,32,31,
30
27
OUT
24MHz/FS2
OUT/IN
48MHz/FS3
26
OUT/IN
X1
3
IN
X2
4
OUT
PWRDWN#
22
IN
SCLK
23
IN
SDATA
24
IN/OUT
VDD
2,9,10,18,25,
29,37
45,47
5,6,14,21,28,
33,41,42
POWER
VDDL
VSS
POWER
POWER
2.5V Power Pins:
Ground Pins: