ICS9148-25

www.DataSheet4U.com Integrated Circuit Systems, Inc. ICS9148-25 Pentium/ProTM System and Cyrix™ Clock Chip General Description The ICS9148-25 is a Clock Synthesizer chip for Pentium and PentiumPro plus Cyrix CPU based Desktop/Notebook systems that will provide all necessary clock timing. Features include four CPU, seven PCI and eight SDRAM clocks. Two reference outputs are available equal to the crystal frequency, plus the IOAPIC output powered by VDDL. Additionally, the device meets the Pentium power-up stabilization, which requires that CPU and PCI clocks be stable within 2ms after power-up. High drive PCICLK and SDRAM outputs typically provide greater than 1 V/ns slew rate into 30pF loads. CPUCLK outputs typically provide better than 1V/ns slew rate into 20pF loads while maintaining 50 ±5% duty cycle. The REF clock outputs typically provide better than 0.5V/ns slew rates. The ICS9148-25 accepts a 14.318MHz reference crystal or clock as its input and runs on a 3.3V supply. Sperad Spectrum is modulated in center-spread mode on CPU/ SDRAM/PCI clocks. Modulation amount is selectable at power-up (latched inputs) for ±0.5, ±1.0, ±2.0 or No spreading. Features Generates system clocks for CPU, IOAPIC, SDRAM, PCI, plus 14.318 MHz ), USB, Plus Super I/O Spread spectrum for CPU/SDRAM/PCI clocks default Supports single or dual processor systems Modulation of Spread Spectrum selectable as ±0.5, ±1.0, ±2.0 or none Supports Intel 60, 66.8MHz, Cyrix 55, 75MHz p...