ICS9148-12

Integrated Circuit Systems, Inc. ICS9148-12 Pentium/ProTM System Clock Chip General Description The ICS9148-12 is a Clock Synthesizer chip for Pentium and PentiumPro CPU based Desktop/Notebook systems that will provide all necessary clock timing. Features include four strong CPU, seven PCI and eight SDRAM clocks. Two reference outputs are available equal to the crystal frequency. Stronger drive CPUCLK outputs typically provide greater than 1 V/ns slew rate into 20pF loads. This device meets rise and fall requirements with 2 loads per CPU output (ie, one clock to CPU and NB chipset, one clock to two L2 cache inputs). PWR_DWN# pin allows low power mode by stopping crystal OSC and PLL stages. For optional power management, CPU_STOP# can stop CPU (0:3) clocks and PCI_STOP# will stop PCICLK (0:5) clocks. CPU and IOAPIC output buffer strength controlled by CPU 3.3_2.5# pin to match VDDL voltage. PCICLK outputs typically provide better than 1V/ns slew rate into 30pF loads while maintaining 50±5% duty cycle. The REF clock outputs typically provide better than 0.5V/ns slew rates. The ICS9148-12 accepts a 14.318MHz reference crystal or clock as its input and runs on a 3.3V core supply. Features • • • • • • • • • • • • • • CPU outputs are stronger drive for multiple loads per pin (ie CPU and NB on one pin) Generates system clocks for CPU, IOAPIC, SDRAM, PCI, plus 14.314 MHz REF(0:1), USB, Plus Super I/O Supports single or dual processor systems I2C serial configuration interface prov...