ICS9248-61

Integrated Circuit Systems, Inc. ICS9248-61 Frequency Timing Generator for Pentium II Systems General Description The ICS9248-61 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 ICS9248-61 employs a proprietary closed loop design, which tightly controls the percentage of spreading over process and temperature variations. Features • Generates the following system clocks: - 2CPU(2.5V) up to 100MHz. - 7 PCI(3.3V) @ 33.3MHz (Includes one free running). - 2 REF clks Fixed (3.3V) 48MHz at 14.318MHz. Skew characteristics: - CPU – CPU<175ps - PCI – PCI < 250ps - PCI_E (early) – PCI = 2.1ns - 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 209mil SSOP. • • • Block Diagram • • Pin Configuration 28 pin SSOP Power Groups GNDR/C = REFCLK, CORE, Crystal VDDCOR = Core GNDLCPU, VDDCPU = CPU GND48, VDD48 = 48MHz VDDPCI, GNDPCI - PCICLK, PCICLK_F, PCICLK_E Pentium is a tra...