General Description

The ICS9248-39 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

• 3.3V outputs: SDRAM, PCI, REF, 48/24MHz

• 2.5V outputs: CPU, IOAPIC

• 20 ohm CPU clock output impedance

• 20 ohm PCI clock output impedance

• Skew from CPU (earlier) to PCI clock - 1.5 to 4 ns, center 2.6 ns.

• No external load cap for CL=18pF crystals

• ±175 ps CPU clock skew

• 250ps (cycle to cycle) CPU jitter

• Smooth frequency switch, with selections from 66.8 to 150 MHz CPU.

• I2C interface for programming

• 3ms power up clock stable time

• Clock duty cycle 45-55.

• 48 pin 300 mil SSOP package

• 3.3V operation, 5V tolerant inputs (with series R)

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