Datasheet > ICS9248-77

ICS9248-77

更新时间： 2024-11-10 22:55:27

品牌	Logo	应用领域
矽成 - ICSI		/
页数	文件大小	规格书
14页	314K
描述
Frequency Timing Generator for PENTIUM II Systems

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数据手册

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ICS9248-77 数据手册

Integrated

Circuit

Systems, Inc.

ICS9248-77

Frequency Timing Generator for PENTIUM II Systems

Pin Configuration

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

theICS9212-01.

Spread Spectrum may be enabled by driving the SPREAD#

pin active. Spread spectrum typically reduces system EMI by

8dBto10dB. ThissimplifiesEMIqualificationwithoutresorting

to board design iterations or costly shielding. The ICS9248-

77 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.

Features

Generates the following system clocks:

- 3 - CPUs @ 2.5V, up to 150MHz.

-3-IOAPIC@2.5V, PCIorPCI/2

-3-3V66MHz@3.3V.

48-pin SSOP

*120K ohm pull-up to VDD on indicated inputs.

- 11-PCIs@3.3V.

-1-48MHz, @3.3Vfixed.

-1-24MHz, @3.3Vfixed.

-1-CPU/2, @2.5V.

± .25% center spread, or 0 to -.5% down spread.

Block Diagram

Usesexternal14.318MHzcrystal.

Key Specification

CPU Output Jitter: <250ps

CPU/2 Output Jitter. <250ps

IOAPIC Output Jitter: <500ps

48MHz, 3V66, PCIOutputJitter:<500ps

Ref Output Jitter. <1000ps

CPU Output Skew: <175ps

IOAPIC Output Skew <250ps

PCI Output Skew: <500ps

3V66OutputSkew<250ps

CPU to 3V66 Output Offset: 0.0 - 1.5ns (CPU leads)

3V66 to PCI Output Offset: 1.5 - 4.0ns (3V66 leads)

CPU to IOAPIC Output Offset 1.5 - 4.0ns (CPU leads)

9248-77Rev C10/20/99

ICS reserves the right to make changes in the device data identified in

this publication without further notice. ICS advises its customers to

obtain the latest version of all device data to verify that any

information being relied upon by the customer is current and accurate.

12 3 4 5 6 7...14

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