ICS951901
Integrated
Circuit
Systems, Inc.
0670B—07/15/04
Programmable Frequency Generator & Integrated Buffers for Pentium III Processor
Block Diagram
Recommended Application:
Single chip clock solution for IA platform.
Output Features:
3 - CPU @ 2.5V
13 - SDRAM @ 3.3V
6 - PCI @3.3V,
2 - AGP @ 3.3V
1 - 48MHz, @3.3V fixed.
1 - 24/48MHz, @3.3V selectable by I
2C
(Default is 24MHz)
2 - REF @3.3V, 14.318MHz.
Features:
Programmable ouput frequency.
Programmable ouput rise/fall time.
Programmable SDRAM and CPU skew.
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.
FS pins for frequency select
Skew Specifications:
CPU - CPU: < 175ps
SDRAM - SDRAM < 250ps (except SDRAM12)
PCI - PCI: < 500ps
CPU (early) - PCI: 1-4ns (typ. 2ns)
Functionality
Pin Configuration
48-Pin 300mil SSOP
* These inputs have a 120K pull down to GND.
1 These are double strength.
PLL2
PLL1
Spread
Spectrum
48MHz
24_48MHz
CPUCLK (2:0)
SDRAM (12:0)
PCICLK (4:0)
AGP (1:0)
PCICLK_F
2
5
13
3
2
X1
X2
XTAL
OSC
CPU
DIVDER
SDRAM
DIVDER
PCI
DIVDER
Stop
SDATA
SCLK
FS(3:0)
PD#
PCI_STOP#
CPU_STOP#
SDRAM_STOP#
MODE
AGP_SEL
Control
Logic
Config.
Reg.
/ 2
REF(1:0)
AGP
DIVDER
VDDA
(AGPSEL)REF0
*(FS3)REF1
GND
X1
X2
VDDPCI
*(FS1)PCICLK_F
*(FS2)PCICLK0
PCICLK1
PCICLK2
PCICLK3
PCICLK4
GND
VDDAGP
AGPCLK0
AGPCLK1
GND
*(FS0)48MHz
*(MODE)24_48MHz
VDD48
SDATA
SCLK
1
*
VDDL
CPUCLK0
CPUCLK1
CPUCLK2
GND
VDDSDR
SDRAM0
SDRAM1
SDRAM2
GND
SDRAM3
SDRAM4
SDRAM5
VDDSDR
SDRAM6
SDRAM7
GND
SDRAM8/PD#
SDRAM9/SDRAM_STOP#
GND
SDRAM10/PCI_STOP#
SDRAM11/CPU_STOP#
SDRAM12
VDDSDR
ICS9519
01
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
FS3FS2
FS1FS0
CPU
SDRAM
PCI
AGP1
AGP0
Bit7
Bit6
Bit5
Bit4
MHz
SEL=1
SEL=0
0
66.67
33.33
66.67
64
0
1
66.67
100.00
33.33
66.67
64
0
1
0
66.67
133.34
33.33
66.67
64
0
1
75.00
37.50
75.00
64
0
1
0
83.31
33.32
66.64
64
0
1
0
1
90.00
30.00
60.00
64
0
1
0
95.00
31.67
63.33
64
0
1
100.00
66.67
33.33
66.67
64
0
1
0
100.00
33.33
66.67
64
0
1
0
1
100.00
133.34
33.33
66.67
64
0
1
0
1
0
105.00
35.00
70.00
64
0
1
0
1
112.00
33.60
67.20
64
0
1
0
117.99
35.40
70.80
64
0
1
0
1
124.09
31.02
62.05
64
0
1
0
133.34
100.00
33.33
66.67
64
0
1
111
133.34
33.33
66.67
64
Bit2