ICS9248-78 Datasheet, PDF (1/13 Pages) Integrated Circuit Systems – Frequency Timing Generator for Pentium II Systems

Integrated
Circuit
Systems, Inc.
ICS9248 - 78
Preliminary Product Preview
Frequency Timing Generator for Pentium II Systems
General Description
The ICS9248-78 is a single chip clock for Intel Pentium II.
It provides all necessary clock signals for such a system.
Spread spectrum may be enabled through I²C programming.
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.
Block Diagram
Features
• 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, 2x PCIMHz.
- 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.
• I²C support for power management.
• Efficient power management scheme through PD#.
• Uses external 14.138 MHz crystal.
Pin Configuration
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
9248-78 Rev A 7/21/99
48-Pin 300 mil SSOP
1. These pins will have 2X drive strength.
* 120K ohm pull-up to VDD on indicated inputs.
Pentium II is a trademark of Intel Corporation
I²C is a trademark of Philips Corporation
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.