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PRODUCT SPECIFICATION
RC7104
3
Pin Descriptions
Pin Name
CPU0:1
Pin Number
22, 21
Type
OUT
Pin Function Description
CPU Clock Outputs 0 through 1:
These two CPU clocks run at
a frequency set by SEL100/66# and the I
2
C bus.
PCI Bus Clock Outputs 1 through 6 and PCI_F:
These seven
PCI clock outputs run synchronously to the CPU clock.
I/O APIC Clock Output:
Provides 14.318MHz fixed frequency.
48MHz Output:
Fixed 48MHz USB clock.
24MHz or 48MHz Output:
Frequency is set by the state of pin
27 on power up.
I/O Dual Function REF and SEL48# pin:
Upon power-up, the
state of SEL48# is latched. The initial state is set by either a 10K
resistor to GND or to VDD. A 10K resistor to GND causes pin 14
to output 48MHz. If the pin is strapped to VDD, pin 14 will output
24MHz. After 2ms, the pin becomes a high drive output that
produces a copy of 14.318MHz.
Frequency Selection Input:
Selects CPU clock frequency as
shown in Table 1.
I
2
C Data Pin:
Data should be presented to this input as
described in the I
2
C section of this data sheet. Internal 250K
ohm pull-up resistor.
I
2
C clock Pin:
The I
2
C Data clock should be presented to this
input as described in the I
2
C section of this data sheet.
Crystal Connection or External Reference Frequency Input:
Connect to either a 14.318MHz crystal or other reference signal.
Crystal Connection:
An input connection for an external
14.318MHz crystal. If using an external reference, this pin must
be left unconnected.
Power Connection:
Power supply for core logic and PLL
circuitry. Connect to 3.3V supply.
Power Connection:
Power supply for PCI_F and PCI1:6.
Connect to 3.3V supply.
Power Connection:
Power supply for IOAPIC output buffer.
Connect to 2.5V supply.
Power Connection:
Power supply for CPU0:1 output buffers.
Connect to 2.5V supply.
Power Connection:
Power supply for 48MHz USB clock.
Connect to 3.3V supply.
Power Connection:
Power supply for 14.318MHz ISA clock.
Connect to 3.3V supply.
Ground Connections:
Connect all ground pins to the common
system ground plane.
PCI_F PCI1:6
4, 5, 6, 7, 8, 10,
11
24
13
14
OUT
IOAPIC
48MHz
24/48MHz
OUT
OUT
OUT
REF/SEL48#
27
IN/OUT
SEL100/66#
16
IN
SDATA
18
IN/OUT
SCLOCK
17
IN
X1
1
IN
X2
2
IN
VDDCORE1
20
POWER
VDDPCI
9
POWER
VDDAPIC
25
POWER
VDDCPU
23
POWER
VDD48
12
POWER
VDDREF
26
POWER
GNDPCI,
GND48, GND-
CPU, GNDREF
3, 15, 19, 28
GROUND