ICS9248-73

Integrated Circuit Systems, Inc. ICS9248-73 Frequency Timing Generator for Pentium II Systems General Description The ICS9248-73 is a single chip clock for Intel Pentium II. It provides all necessary clock signals for such a system. Spread spectrum may be enabled through I2C programming. Spread spectrum typically reduces EMI by 8dB to 10 dB. This simplifies EMI qualification without resorting to board design iterations or costly shielding. The ICS9248-73 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 - CPUs @ 2.5V , up to 150MHz. - 1 - IOAPIC @ 2.5V, PCI/2MHz. - 9 - SDRAMs @ 3.3V, up to 150MHz. - 2 - 3V66 @ 3.3V, 2x PCI MHz. - 8 - PCIs @ 3.3V. - 2 - 48MHz, @ 3.3V fixed. - 1 - REF @ 3.3V, 14.318MHz. - 1 - 24_48MHz, @ 3.3V fixed. Supports spread spectrum modulation , down spread 0 to -0.5%, ±0.25% center spread. I2C support for power management Efficient power management scheme through PD# Uses external 14.138 MHz crystal • • • • Block Diagram Pin Configuration 48-Pin 300 mil SSOP *120K ohm pull-up to VDD on indicated inputs. **60K ohm pull-up to VDD on indicated inputs. 1. These pins will have 2x drive strength Power Groups GNDREF, VDDREF = REF & Crystal GND3V66, VDD3V66 = 3V66 GNDPCI, VDDPCI = PCICLK GNDCOR, VDDCOR = PLL core GND48, VDD48 = 48MHz GNDSDR, VDDSDR = SDRAM GNDLCPU, VDDLCPU = CPUCLK GNDAPIC, VDDAPIC = IOAPIC ICS reserv...