CY24242
Document #: 38-07268 Rev. *B
Page 2 of 10
Pin Definitions
Pin Name
Pin
No.
Pin
Type
Pin Description
CPU0:3
24, 23, 21,
20
O
CPU Clock Outputs: These four outputs run at a frequency set by FS0:1. The
width of the Spread Spectrum Modulation is enabled by pin SSON#, and
selected by pins SS%0:1.
SDRAM0:3
10, 9, 7, 6
O
SDRAM Outputs: These four SDRAM clock outputs run synchronously to the
CPU clock. Modulation and frequency follow the CPU outputs.
FS0:1
15, 16
I
Frequency Selection Inputs: Selects CPU clock frequency as shown in
Table 1.
SS%0:1
14, 18
I
Modulation Width Selection Inputs: These inputs select the width of the
Spread Spectrum feature when it is enabled by SSON#.
USBCLK
26
O
USB Output: Timing signal running at 48.0080 MHz when a 14.31818-MHz
frequency is provided as the reference. (167 ppm accuracy to 48 MHz, the
output is equal to the reference times 57/17.)
SSON#
17
I
CPU Spread Spectrum Enable Input: When this pin is pulled LOW, outputs
CPU0:3 and SDRAM0:3 will have the Spread Spectrum Feature enabled.
USBCLKEN
28
I
USB Disable Input: When this pin is pulled LOW, output USBCLK will be
disabled to a LOW state.
REF
2
O
Reference Output: This output will be equal in frequency to the reference
signal provided at X1/X2.
SDEN
13
I
SDRAM Bank Disable Input: When this pin is pulled LOW, outputs SDRAM0:3
will be disabled to a LOW state.
X1
4
I
Crystal Connection or External Reference Frequency Input: Connect to
either a 14.318-MHz crystal or other reference signal.
X2
5
I
Crystal Connection: An input connection for an external 14.318-MHz crystal.
If using an external reference, this pin must be left unconnected.
VDDCORE
1, 12
P
Power Connection: Core Power supply. Connect to 3.3V supply.
VDDU
25
P
Power Connection: Power supply for the USB output. Connect to 3.3V or 2.5V
supply.
VDDC
22
P
Power Connection: Power supply for the CPU outputs. Connect to 3.3V or
2.5V supply.
VDDS
8
P
Power Connection: Power supply for the SDRAM outputs. Connect to 3.3V
or 2.5V supply.
GND
3,11, 19, 27
G
Ground Connections: Connect all ground pins to the common system ground
plane.
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