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ICS9248-77 - Frequency Timing Generator

Datasheet Summary

Description

The ICS9248-77 is a main clock synthesizer chip for Pentium II based systems using Rambus Interface DRAMs.

This chip provides all the clocks required for such a system when used with a Direct Rambus Clock Generator(DRCG) chip such as the ICS9212-01.

Features

  • • Generates the following system clocks: - 3 - CPUs @ 2.5V, up to 150MHz. - 3 - IOAPIC @ 2.5V, PCI or PCI/2 - 3 - 3V66MHz @ 3.3V. - 11 - PCIs @ 3.3V. - 1 - 48MHz, @ 3.3V fixed. - 1 - 24MHz, @ 3.3V fixed. - 1 - CPU/2, @ 2.5V. • ± .25% center spread, or 0 to -.5% down spread. • Uses external 14.318MHz crystal. Pin Configuration 48-pin SSOP.
  • 120K ohm pull-up to VDD on indicated inputs. Block Diagram Key Specification • CPU Output Jitter:.

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Datasheet Details

Part number ICS9248-77
Manufacturer Renesas
File Size 641.92 KB
Description Frequency Timing Generator
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ICS9248-77 Frequency Timing Generator for PENTIUM II Systems General Description The ICS9248-77 is a main clock synthesizer chip for Pentium II based systems using Rambus Interface DRAMs. This chip provides all the clocks required for such a system when used with a Direct Rambus Clock Generator(DRCG) chip such as the ICS9212-01. Spread Spectrum may be enabled by driving the SPREAD# pin active. Spread spectrum typically reduces system EMI by 8dB to 10dB. This simplifies EMI qualification without resorting to board design iterations or costly shielding. The ICS924877 employs a proprietary closed loop design, which tightly controls the percentage of spreading over process and temperature variations. The CPU/2 clocks are inputs to the DRCG.
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