PRELIMINARY INFORMATION
ICS650-21
System Peripheral Clock Source
PSEL0
0
M
1
0
M
1
0
M
1
PCLK1
25.00
37.5
66.66
40.00
33.3334
20.00
20.00
20.00
50
PCLK2,3
50.00
75.00
133.33
80.00
66.6667
40.00
33.3334
66.6667
100
Pin Assignment
USEL
X2
X1/ICLK
VDD
VDD
GND
UCLK
20M
ACLK
25M
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
PSEL1
PSEL0
PCLK2
PCLK3
VDD
ASEL
GND
OFF/14.318M
PCLK1
OE
Processor Clock (MHz)
PSEL1
0
0
0
M
M
M
1
1
1
Audio Clock (MHz)
ASEL
0
M
1
ACLK
49.152
24.576
14.318
USB Clock (MHz)
USEL
0
M
1
UCLK
12
24
48
20 pin (150 mil) SSOP
Pin Descriptions
Pin #
1
2
3
4
5
6
7
0 = connect directly to ground, 1 = connect directly
to VDD, M=leave unconnected (floating)
8
9
10
11
12
13
14
15
16
17
18
19
20
Name
USEL
X2
X1/ICLK
VDD
VDD
GND
UCLK
20M
ACLK
25M
OE
PCLK1
OFF/14.318M
GND
ASEL
VDD
PCLK3
PCLK2
PSEL0
PSEL1
Type
I
XO
XI
P
P
P
O
O
O
O
I
O
O
P
I
P
O
O
I
I
Description
UCLK Select pin. Determines frequency of USB clock per table above.
Crystal connection. Connect to parallel mode 25 MHz crystal. Leave open for clock.
Crystal connection. Connect to parallel mode 25 MHz crystal, or clock.
Connect to VDD. Must be same value as other VDD. Decouple with pin 6.
Connect to VDD. Must be same value as other VDD.
Connect to ground.
USB clock output per table above.
Fixed 20 MHz output for Ethernet.
AC97 Audio clock output per table above.
Fixed 25 MHz reference output for Fast Ethernet.
Output Enable. Tri-states all outputs when low.
PCLK output number 1 per table above.
14.31818 MHz clock output only when ASEL=VDD.
Connect to ground.
ACLK Select pin. Determines frequency of Audio clock per table above.
Connect to VDD. Must be same value as other VDD. Decouple with pin 14.
PCLK output number 3 per table above.
PCLK output number 2 per table above.
Processor Select pin #0. Determines frequencies on PCLKs 1-3 per table above.
Processor Select pin #1. Determines frequencies on PCLKs 1-3 per table above.
Key: I = Input; XO/XI = crystal connections; O = output; P = power supply connection
MDS 650-21 A
2
Revision 010301
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408) 295-9800tel • www.icst.com
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