
Integrated
Circuit
Systems, Inc.
ICS94235
Third party brands and names are the property of their respective owners.
Block Diagram
94235 Rev A 01/17/02
Functionality
FS3
0
0
0
0
0
0
0
0
1
1
1
1
1
0
1
1
Pin Configuration
Recommended Application:
Output Features:
1 - Differential pair open drain CPU clocks
1 - Single-ended open drain CPU clock
13 - SDRAM @ 3.3V
7 - PCI @ 3.3V
2 - AGP @ 3.3V
1 - 48MHz, @3.3V
1 - REF @ 3.3V, (selectable strength) through I
2
C
Features:
Programmable ouput frequency
Programmable ouput rise/fall time
Programmable CPU, SDRAM, PCI and AGP skew
Real time system reset output
Spread spectrum for EMI control typically
by 7dB to 8dB, with programmable spread percentage
Watchdog timer technology to reset system
if over-clocking causes malfunction
Uses external 14.318MHz crystal
Skew Specifications:
CPUT - CPUC: <250ps
PCI - PCI: <500ps
CPU - SDRAM: <350ps
SDRAM - SDRAM: <250ps
AGP - AGP: <250ps
AGP - PCI: <750ps
CPU - PCI: <3ns
48-Pin 300mil SSOP &
240mil TSSOP package
RESET#
*PD#
GND
X1
X2
AVDD
**FS0/REF0
VDD
**FS1/AGP0
AGP1
GND
*FS2/PCICLK_F
PCICLK0
PCICLK1
PCICLK2
GND
VDD
*MODE/PCICLK3
PCICLK4
PCICLK5
AVDD48
**FS3/48MHz
GND
SCLK
GND
CPUCLKT0
CPUCLKC0
CPUCLKT1
SDATA
SDRAM0
SDRAM1
GND
VDD
SDRAM2
SDRAM3
SDRAM4
SDRAM5
VDD
GND
SDRAM6
SDRAM7
SDRAM8
SDRAM9
GND
VDD
SDRAM10(PCI_STOP#)*
SDRAM11
SDRAM12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
PLL2
PLL1
Spread
Spectrum
48MHz
CPUCLKT (1:0)
SDRAM (12:0)
PCICLK (5:0)
AGP (1:0)
RESET#
2
6
13
2
PCICLK_F
CPUCLKC0
X1
X2
XTAL
OSC
DCPU
SDRAM
PCI
DIVDER
AGP
DIVDER
Stop
Stop
Stop
SDATA
SCLK
FS (3:0)
PD#
PCI_STOP#
MODE
Control
Logic
Config.
Reg.
REF0
Power Groups
FS2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
FS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
FS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
CPU
66.66
66.66
100.00
100.00
100.00
120.00
133.33
133.33
90.00
100.90
100.00
100.00
100.00
126.00
133.33
133.33
SDRAM
66.66
100.00
66.66
100.00
133.33
120.00
100.00
133.33
90.00
100.90
66.66
100.00
133.33
126.00
100.00
133.33
PCI
33.33
33.33
33.33
33.33
33.33
30.00
33.33
33.33
30.00
33.63
33.33
33.33
33.33
31.50
33.33
33.33
AGP
66.66
66.66
66.66
66.66
66.66
60.00
66.66
66.66
60.00
67.27
66.66
66.66
66.66
63.00
66.66
66.66