ICS9248-61 Datasheet | Integrated Circuit Systems

Integrated Circuit Systems, Inc. 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. 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. • • • 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 trademark on Intel Corporation. 9248-61 Rev B 1/8/99 ICS reserves the right to make changes in the device data identified in this publication without further notice. ICS advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate. Pin Descriptions Pin number 2 3 4 7 8 12 13 14 15 16 17 Pin name X1 X2 PCICLK_F GNDPCI VDDPCI PCICLK_E VDD48 SEL 100_66#/ 48MHz GND48 DIV4#...