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Integrated Circuit Systems, Inc.
ICS94236
Programmable System Clock Chip for AMD - K7™ processor
Recommended Application: VIA KX/KT133 style chipset Output Features: • 1 - Differential pair open drain CPU clocks • 1 - CPU clock @ 3.3V • 13 - SDRAM @ 3.3V • 6 - PCI @3.3V, • 1 - 48MHz, @3.3V fixed. • 1 - 24/48MHz @ 3.3V • 2 - REF @3.3V, 14.318MHz. Features: • Programmable ouput frequency. • Programmable ouput rise/fall time. • Programmable PCI_F and PCICLK 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
Pin Configuration
VDDREF REF0 GND X1 X2 VDDPCI 1 FS4/PCICLK_F **FS3/PCICLK0 GND *SEL24_48#/PCICLK1 PCICLK2 PCICLK3 PCICLK4 VDDPCI BUFFER IN GND SDRAM11 SDRAM10 VDDSDR SDRAM9 SDRAM8 GND SDATA SCLK 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 REF1/FS2** GND CPUCLK GND CPUCLKC0 CPUCLKT0 VDDCPU PD#* SDRAM_OUT GND SDRAM0 SDRAM1 VDDSDR SDRAM2 SDRAM3 GND SDRAM4 SDRAM5 VDDSDR SDRAM6 SDRAM7 VDD48 48MHz/FS0* 24/48MHz/FS1**
48-Pin 300mil SSOP
* ** 1 Internal Pull-up Resistor of 120K to VDD. Internal Pull-down Resistor of 120K to GND. Internal Pull-down Resistor of 60K to GND.
Block Diagram
PLL2 /2 X1 X2 XTAL OSC PLL1 Spread Spectrum 48MHz 24_48MHz
Functionality
FS3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 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 (MHz) 95.00 100.00 102.00 105.00 110.00 113.00 115.00 120.00 133.33 135.00 137.00 139.00 141.00 143.00 145.00 150.00 PCICLK (MHz) 31.67 33.33 34.00 35.00 36.67 37.67 38.33 40.00 33.33 33.75 34.25 34.75 35.25 35.75 36.25 37.50
REF (1:0) CPUCLK
CPU DIVDER
CPUCLKC0 CPUCLKT0
SEL24_48# SDATA SCLK FS (4:0) PD#
Control Logic Config. Reg.
PCI DIVDER
PCICLK (4:0) PCICLK_F
SDRAM DRIVER
SDRAM (11:0) SDRAM_OUT
BUFFER IN
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0451A—01/10/03
* 16 additional frequency selectables via FS4, refer to page5 for frequency table.
ICS94236
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ICS94236
General Description
The ICS94236 is a main clock synthesizer chip for AMD-K7 based systems with VIA style chipset. This provides all clocks required for such a system. The ICS94236 belongs to ICS new generation of programmable system clock generators. It employs serial programming I2C interface as a vehicle for changing output functions, changing output frequency, configuring output strength, configuring output to output skew, changing spread spectrum amount, changing group divider ratio and dis/ enabling individual clocks. This device also has ICS propriety 'Watchdog Timer' technology which will reset the frequency to a safe setting if the system become unstable from over clocking.
Pin Descriptions
PIN NUMBER 1 2 3,9,16,22, 33,39,45, 47 4 5 6,14 7 FS4 2 8 10 11, 12, 13 15 .