ICS9148-03

Integrated Circuit Systems, Inc. ICS9148-03 Frequency Generator & Integrated Buffers for PENTIUM/ProTM The ICS9148-03 generates all clocks required for high speed RISC or CISC microprocessor systems such as Intel PentiumPro or Cyrix. Eight different reference frequency multiplying factors are externally selectable with smooth frequency transitions. Features include four CPU, seven PCI and Twelve SDRAM clocks. Two reference outputs are available equal to the crystal frequency. Plus the IOAPIC output powered by VDDL1. One 48 MHz for USB, and one 24 MHz clock for Super IO. Spread Spectrum built in - ±1.5% modulation to reduce the EMI. Rise time adjustment for VDD at 3.3V or 2.5V CPU. Additionally, the device meets the Pentium power-up stabilization, which requires that CPU and PCI clocks be stable within 2ms after power-up. It is not recommended to use I/O dual function pin for the slots (ISA, PCI, CPU, DIMM). The add on card might have a pull up or pull down. 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 and 24 and 48 MHz clock outputs typically provide better than 0.5V/ns slew rates. General Description Features • • • • • • • • • • • • 3.3V outputs: SDRAM, PCI, REF, 48/24MHz. 2.5V or 3.3V outputs: CPU, IOAPIC 20 ohm CPU clock output impedance 20 ohm PCI clock output impedance Skew from CPU (earlier) ...