Integrated

Circuit

Systems, Inc.

General Description

Features

ICS9248-78

Block Diagram

Pentium II is a trademark of Intel Corporation

I

Frequency Timing Generator for Pentium II Systems

9248-78 Rev A 7/21/99

Pin Configuration

•

Generates the following system clocks:

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

- 1 - IOAPIC @ 2.5V, PCI/2MHz.

- 9 SDRAMs (3.3V), up to150MHz.

-2-3V66@3.3V,2xPCIMHz.

- 8 - PCIs @ 3.3V.

- 1 - 48MHz, @ 3.3V fixed.

-2-REF@3.3V,14.318Hz.

- 1 - 24MHz, @ 3.3V fixed.

•

Supports spread spectrum modulation ,

down spread 0 to -0.5%, ±0.25% center spread.

•

Efficient power management scheme through PD#.

•

Uses external 14.138 MHz crystal.

48-Pin 300 mil SSOP

The ICS9248-78 is a single chip clock for Intel Pentium II.

It provides all necessary clock signals for such a system.

Spread spectrum typically reduces EMI by 8dB to 10 dB.

This simplifies EMI qualification without resorting to board

design iterations or costly shielding. The ICS9248-78

employs a proprietary closed loop design, which tightly

controls the percentage of spreading over process and

temperature variations.

Power Groups

GNDREF,VDDREF=REF,Crystal

GND3V66,VDD3V66=3V66

GNDPCI,VDDPCI=PCICLKs

GNDCOR,VDDCOR=PLLCORE

GND48,VDD48=48

GNDSDR,VDDSDR=SDRAM

GNDLCPU,VDDLCPU=CPUCLK

GNDLPCI,VDDLAPIC=IOAPIC

1. These pins will have 2X drive strength.

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

Preliminary Product Preview

PRODUCT PREVIEW documents contain information on new

products in the sampling or preproduction phase of development.

Characteristic data and other specifications are subject to change

without notice.