W312-02
Document #: 38-07259 Rev. *B
Page 2 of 21
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Pin Definitions
Pin Name
Pin No.
Pin
Type
Pin Description
REF0/FS0
48
I/O
Reference Clock Output 0/Frequency Select 0: 3.3V 14.318-MHz clock out-
put. REF0 will be disabled when REF_STOP# is active. This pin also serves
as the select strap to determines device operating frequency as described in
Table 4.
REF1/FS1
47
I/O
Reference Clock Output 0/Frequency Select 1: 3.3V 14.318-MHz clock out-
put. REF1 will be disabled when REF_STOP# is active. This pin also serves
as the select strap to determines device operating frequency as described in
Table 4.
REF2
46
I/O
Reference Clock Output 2: 3.3V 14.318-MHz clock output. REF2 will be dis-
abled when REF_STOP# is active.
X1
3
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Crystal Input: This pin has dual functions. It can be used as an external
14.318-MHz crystal connection or as an external reference frequency input.
X2
4
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Crystal Output: An input connection for an external 14.318-MHz crystal con-
nection. If using an external reference, this pin must be left unconnected.
PCI_F/FS4
9
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Free-Running PCI Clock/Frequency Select 4: 3.3V 33-MHz free running PCI
clock output. This pin also serves as the select strap to determines device
operating frequency as described in Table 4.
PCI_0/SEL24_48#
10
I/O
PCI Clock 0/Select 24 or 48 MHz: 3.3V 33-MHz PCI clock outputs. This output
will be disabled when PCI_STOP# is active. This pin also serves as the select
strap to determine device operating frequency of 24_48MHz output.
PCI1:8
11, 13, 14, 16,
17, 18, 20, 21
O
PCI Clock 1 through 8: 3.3V 33-MHz PCI clock outputs. PCI1:8 will be dis-
abled when PCI_STOP# is active.
PCI9_E
22
O
Early PCI Clock 9: 3.3V 33-MHz PCI clock outputs. PCI9_E will be disabled
when PCI_STOP# is active.
AGP0:2
26, 27, 28
O
AGP Clock 0 through 2: 3.3V 66-MHz clock outputs. The operating frequency
is controlled by FS0:4 (see Table 4). AGP0:2 will be disabled when
AGP_STOP# is active.
48MHz/FS2
6
I/O
48-MHz Output/Frequency Selection 3: 3.3V 48-MHz non-spread spectrum
output. 48MHz will be disabled when REF_STOP# is active. This pin also
serves as the select strap to determine device operating frequency as de-
scribed in Table 4.
24_48MHz/FS3
7
I/O
24 or 48-MHz Output/Select 24 or 48 MHz: 3.3V 24 or 48-MHz non-spread
spectrum output. 24_48MHz will be disabled when REF_STOP# is active. This
pin also serves as the select strap to determine device operating frequency as
described in Table 4.
RST#
24
O
(open-
drain)
Reset#: Open-drain RESET# output.
CPUT0, CPUC0
42, 41
O
(open-
drain)
CPU Clock Output 0: CPUT0 and CPUC0 are the differential CPU clock out-
puts for the K7 processor. They are open-drain outputs.
CPUT_CS,
CPUC_CS
39, 38
O
CPU Clock Output for Chipset: CPUT_CS and CPUC_CS are the differential
CPU clock outputs for the chipset. They are push-pull outputs. These outputs
will be disabled when CPU_STOP# is active.
CPU_STOP#
36
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CPU STOP Input: This input will disable CPUT_CS and CPUC_CS when it is
active.
PCI_STOP#
35
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PCI STOP Input: This input will disable PCI0:8 and PCI9_E when it is active.
AGP_STOP#
44
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AGP STOP Input: This input will disable AGP0:2 when it is active.
REF_STOP#
45
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REF STOP Input: This input will disable REF0:2, 24_48MHz and 48 MHz
outputs when it is active.