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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 • 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 plus 83.3 and 68MHz (Turbo of 66.6) speeds. • Synchronous clocks skew matched to 250ps window on CPU, SDRAM and 500ps window on PCI clocks • CPU clocks to PCI clocks skew 1-4ns (CPU early) • MODE input pin selects optional power management input control pins • Two fixed outputs, 48MHz and 24 MHz • Separate 2.5V and 3.3V supply pins - 2.5V or 3.3V output: CPU, IOAPIC (Strength selectable) - 3.3V outputs: SDRAM, PCI, REF, 48/24 MHz • No power supply sequence requirements • 48 pin 300 mil SSOP
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