ICS9248-61 Datasheet | Renesas

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 8d B to 10d B. 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. Block Diagram 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=18p F crystal. • 28 pin 209mil SSOP. Pin Configuration Power Groups GNDR/C = REFCLK, CORE, Crystal VDDCOR = Core GNDLCPU, VDDCPU = CPU GND48, VDD48 = 48MHz VDDPCI, GNDPCI - PCICLK, PCICLK_F, PCICLK_E 28 pin SSOP Pentium is a trademark on Intel Corporation. Pin Descriptions Pin number 2 3 4 7 8 12 13 15 16 19 20 21 22 25 26 28 1,27 23,24 5,6,9,10, 11 Pin...