ICS9248-127 Datasheet | Integrated Circuit Systems

Integrated Circuit Systems, Inc. Frequency Generator & Integrated Buffers for PENTIUM/Pro TM General Description The ICS9248-127 is the single chip clock solution for Desktop designs using the VIA MVP4 and Aladdin 7 style chipset. It provides all necessary clock signals for such a system. Spread spectrum may be enabled through I2C programming. Spread spectrum typically reduces system EMI by 8d B to 10d B. This simplifies EMI qualification without resorting to board design iterations or costly shielding. The ICS9248127 employs a proprietary closed loop design, which tightly controls the percentage of spreading over process and temperature variations. Features - - - - Up to 124MHz frequency support. Spread Spectrum for EMI control 0 to -0.5% down spread and ±0.25% center spread Serial I2C interface for Power Management, Frequency Select, Spread Spectrum. Provides the following system clocks - 4-CPUs @ 3.3V, up to 124MHz. - 13-SDRAMs @3.3V, up to 124MHz (including SDRAM_F) - 6-PCI (including 1 free running, PCICLK_F) @3.3V, CPU/2 or CPU/3. - 1-24MHz @3.3V fixed. - 1-48MHz @3.3V fixed. - 2-REF @3.3V, 14.318MHz. Efficient Power management scheme through PCI and STOP CLOCKS. - Block Diagram PLL2 /2 X1 X2 BUFFER IN CPUCLK_F PLL1 Spread Spectrum FS(3:0) MODE STOP 48MHz 24MHz REF (1:0) Pin Configuration VDDREF - PCI_STOP#/REF0 GND X1 X2 VDDPCI - MODE/PCICLK_F - FS3/PCICLK0 GND 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- VDDCPU CPUCLK_F CPUCLK0 GND CPUCLK1 CPUCLK2 CLK_STOP# GND SDRAM_F SDRAM0 SDRAM1 VDDSDR SDRAM2 SDRAM3 GND SDRAM4 SDRAM5 VDDSDR SDRAM6 SDRAM7 VDD48 48MHz/FS0- 24MHz/FS1- XTAL OSC CPUCLK (2:0) LATCH STOP SDRAM (11:0) SDRAM_F CLK_STOP# PCI_STOP# SDATA SCLK Control Logic Config. Reg. PCI CLOCK...