ICS951901 Datasheet, PDF (1/19 Pages) Integrated Circuit Systems – Programmable Frequency Generator & Integrated Buffers for Pentium III Processor

Integrated
Circuit
Systems, Inc.
ICS951901
Programmable Frequency Generator & Integrated Buffers for Pentium III Processor
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 I²C
(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)
Pin Configuration
VDDA
1
1_{*(AGPSEL)REF0}
2
1_*(FS3)REF1
3
GND
4
X1
5
X2
6
VDDPCI
7
*(FS1)PCICLK_F
8
*(FS2)PCICLK0
9
PCICLK1
10
PCICLK2
11
PCICLK3
12
PCICLK4
13
GND
14
VDDAGP
15
AGPCLK0
16
AGPCLK1
17
GND
18
GND
19
*(FS0)48MHz
20
*(MODE)24_48MHz
21
VDD48
22
SDATA
23
SCLK
24
48
VDDL
47
CPUCLK0
46
CPUCLK1
45
CPUCLK2
44
GND
43
VDDSDR
42
SDRAM0
41
SDRAM1
40
SDRAM2
39
GND
38
SDRAM3
37
SDRAM4
36
SDRAM5
35
VDDSDR
34
SDRAM6
33
SDRAM7
32
GND
31
SDRAM8/PD#
30
SDRAM9/SDRAM_STOP#
29
GND
28
SDRAM10/PCI_STOP#
27
SDRAM11/CPU_STOP#
26
SDRAM12
25
VDDSDR
48-Pin 300mil SSOP
* These inputs have a 120K pull down to GND.
1 _{These are double strength.}
Block Diagram
PLL2
X1
XTAL
X2
OSC
PLL1
Spread
Spectrum
SDATA
SCLK
FS(3:0)
PD#
PCI_STOP#
CPU_STOP#
SDRAM_STOP#
MODE
AGP_SEL
Control
Logic
Config.
Reg.
/2
CPU
DIVDER
Stop
SDRAM
DIVDER
Stop
PCI
DIVDER
Stop
AGP
DIVDER
48MHz
24_48MHz
REF(1:0)
2
CPUCLK (2:0)
3
SDRAM (12:0)
13
PCICLK (4:0)
5
PCICLK_F
AGP (1:0)
2
Functionality
FS3 FS2 FS1
Bit2 Bit7 Bit6 Bit5
00
0
0
00
0
0
00
0
1
00
0
1
00
1
0
00
1
0
00
1
1
00
1
1
01
0
0
01
0
0
01
0
1
01
0
1
01
1
0
01
1
0
01
1
1
01
1
1
FS0 CPU SDRAM
Bit4 MHz MHz
0 66.67 66.67
1 66.67 100.00
0 66.67 133.34
1 75.00 75.00
0 83.31 83.31
1 90.00 90.00
0 95.00 95.00
1 100.00 66.67
0 100.00 100.00
1 100.00 133.34
0 105.00 105.00
1 112.00 112.00
0 117.99 117.99
1 124.09 124.09
0 133.34 100.00
1 133.34 133.34
PCI
MHz
33.33
33.33
33.33
37.50
33.32
30.00
31.67
33.33
33.33
33.33
35.00
33.60
35.40
31.02
33.33
33.33
AGP1
SEL=1
66.67
66.67
66.67
75.00
66.64
60.00
63.33
66.67
66.67
66.67
70.00
67.20
70.80
62.05
66.67
66.67
AGP0
SEL=0
64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
0670B—07/15/04