ICS9248-56 Datasheet, PDF (1/11 Pages) Integrated Circuit Systems – Frequency Timing Generator for Pentium II Systems

Integrated
Circuit
Systems, Inc.
ICS9248-56
Frequency Timing Generator for Pentium II Systems
General Description
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.
Block Diagram
Features
• 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
• Skew characteristics:
- CPU – CPU<175ps
- PCI – PCI < 500ps
- CPU(early) – PCI = 1.5ns – 4ns.
• Supports Spread Spectrum modulation for CPU and PCI
clocks, 0.5% down spread
• Efficient Power management scheme through stop clocks
and power down modes.
• Uses external 14.318MHz crystal, no external load cap
required for CL=18pF crystal.
• 28 pin 209mil SSOP and 173mil TSSOP
Pin Configuration
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
9248-56 Rev E 12/27/00
28 pin SSOP and TSSOP
Pentium is a trademark on Intel Corporation.
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.