ICS9248-50

Integrated Circuit Systems, Inc. ICS9248-50 Frequency Timing Generator for Pentium II Systems General Description The ICS9248-50 is the Main clock solution for Notebook designs using the Intel 440BX style chipset. Along with an SDRAM buffer such as the ICS9179-03, it provides all necessary clock signals for such a system. Spread spectrum may be enabled by driving pin 26, SPREAD# active (Low) at power-on. Spread spectrum typically reduces system EMI by 8dB to 10dB. This simplifies EMI qualification without resorting to board design iterations or costly shielding. The ICS9248-50 employs a proprietary closed loop design, which tightly controls the percentage of spreading over process and temperature variations. Features Generates the following system clocks: - 2 CPU (2.5V) up to 100MHz. - 6 PCI (3.3V) @ 33.3MHz (Includes one free running). - 2 REF clks (3.3V) at 14.318MHz. Skew characteristics: - CPU – CPU<175ps - PCI – PCI < 500ps - CPU(early) – PCI = 1.5ns – 4ns. Supports Spread Spectrum modulation for CPU and PCI clocks, 0.5% down spread Efficient Power management scheme through stop clocks and power down modes. Uses external 14.318MHz crystal, no external load cap required for CL=18pF crystal. 28-pin (209 mil) SSOP and (6.1mm) TSSOP package Block Diagram Pin Configuration 28-Pin SSOP & TSSOP Power Groups VDD, GND = PLL core VDDREF, GNDREF = REF(0:1), X1, X2 VDDPCI, GNDPCI = PCICLK_F, PCICLK (0:4) VDD48, GND48 = 48MHz, 48/24MHz Pentium is a trademark on ...