CY28316
Document #: 38-07125 Rev. *B
Page 2 of 18
Pin Definitions
Pin Name
Pin No.
Pin Type
Pin Description
CPU0:1
44, 43
O
CPU Clock Output 0 through 1: CPU clocks for processor and chipset.
PCI2:6
9, 10, 11, 12,
13
O
PCI Clock Outputs 2 through 6: 3.3V 33-MHz PCI clock outputs. Frequency is
set by FS0:4 inputs or through serial data interface.
PCI1/FS3
7
I/O
Fixed PCI Clock Output/Frequency Select 3: 3.3V PCI clock outputs. As an
output, frequency is set by FS0:4 inputs or through the serial data interface. This
pin also serves as a power-on strap option to determine the device operating
frequency, as described in Table 5.
PCI0/FS4
6
I/O
Fixed PCI Clock Output/Frequency Select 4: 3.3V PCI clock outputs. This pin
also serves as a power-on strap option to determine the device operating
frequency, as described in Table 5.
RST#
41
O
(open-drain)
Reset# Output: Open drain system reset output.
48MHz/FS0
26
I/O
48-MHz Output/Frequency Select 0: 3.3V 48-MHz non-spread spectrum output.
This pin also serves as a power-on strap option to determine the device operating
frequency as described in Table 5.
24_48MHz/
FS1
25
I/O
24_48MHz Output/Frequency Select 1: 3.3V 24- or 48-MHz non-spread
spectrum output. This pin also serves as a power-on strap option to determine the
device operating frequency, as described in Table 5.
REF1/FS2
46
I/O
Reference Clock Output 1/Frequency Select 2: 3.3V 14.318-MHz output clock.
This pin also serves as a power-on strap option to determine the device operating
frequency as described in Table 5.
REF0
47
O
Reference Clock Output 0: 3.3V 14.318-MHz output clock.
SDRAMIN
15
I
SDRAM Buffer Input Pin: Reference input for SDRAM buffer.
SDRAM0:12
38, 37, 35, 34,
32, 31, 29, 28,
21, 20, 18, 17,
40
O
SDRAM Outputs: These thirteen dedicated outputs provide copies of the signal
provided at the SDRAMIN input.
SCLK
24
I
Clock pin for SMBus circuitry.
SDATA
23
I/O
Data pin for SMBus circuitry.
X1
3
I
Crystal Connection or External Reference Frequency 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
O
Crystal Connection: An output connection for an external 14.318-MHz crystal. If
using an external reference, this pin must be left unconnected.
VTT_PWRGD#
48
I
VTT_PWRGD#: 3.3V LVTTL compatible input that controls the FS0:4 to be latched
and enables all outputs. CY28316 will sample the FS0:4 inputs and enable all clock
outputs after all VDD become valid and VTT_PWRGD# is held LOW.
VDD_REF,
VDD_PCI,
VDD_SDRAM,
VDD_48MHz
1, 5, 14, 19,
27, 30, 36
P
Power Connection: Power supply for core logic, PLL circuitry, SDRAM outputs,
PCI outputs, reference outputs, 48-MHz output, and 24_48-MHz output. Connect
to 3.3V supply.
VDD_CPU
42
P
Power Connection: Power supply for CPU outputs. Connect to 2.5V supply.
GND_REF,
GND_PCI,
GND_SDRAM,
VDD_48MHz,
VDD_CPU
2, 8, 16, 22,
33, 39, 45
G
Ground Connections: Connect all ground pins to the common system ground
plane.
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