Integrated

Circuit

Systems, Inc.

General Description

Features

ICS9248-56

Block Diagram

Frequency Timing Generator for Pentium II Systems

9248-56 Rev E 12/27/00

Pin Configuration

28 pin SSOP and TSSOP

Pentium is a trademark on Intel Corporation.

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Generates the following system clocks:

- 2CPU(2.5V) up to 100MHz.

- 6 PCI(3.3V) @ 33.3MHz (Includes one free running).

- 1 REF clks (3.3V) at 14.318MHz.

- 1 Fixed clock at 48MHz

- 1 Fixed clock at 48 or 24MHz

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Skew characteristics:

- CPU – CPU<175ps

- PCI – PCI < 500ps

- CPU(early) – PCI = 1.5ns – 4ns.

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Supports Spread Spectrum modulation for CPU and PCI

clocks, 0.5% down spread

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Efficient Power management scheme through stop clocks

and power down modes.

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Uses external 14.318MHz crystal, no external load cap

required for CL=18pF crystal.

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28 pin 209mil SSOP and 173mil TSSOP

The ICS9248-56 is the Main clock solution for Notebook

designs using the Intel 440BX style chipset. Along with an

SDRAM buffer such as the ICS9179-03, it provides all

necessary clock signals for such a system.

Spread spectrum may be enabled by driving pin 26, SPREAD#

active (Low) at power-on. Spread spectrum typically reduces

system EMI by 8dB to 10dB. This simplifies EMI qualification

without resorting to board design iterations or costly shielding.

The ICS9248-56 employs a proprietary closed loop design,

which tightly controls the percentage of spreading over

process and temperature variations.

Power Groups

VDD, GND = PLL core

VDDREF,GNDREF=REF(0:1),X1,X2

VDDPCI, GNDPCI = PCICLK_F, PCICLK (0:4)

VDD48, GND48 = 48MHz, 48/24MHz

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.