ICS9148-58 Datasheet, PDF (1/14 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for PENTIUM/ProTM

Integrated
Circuit
Systems, Inc.
ICS9148 - 58
Frequency Generator & Integrated Buffers for PENTIUM/Pro^TM
General Description
The ICS9148-58 is the single chip clock solution for Desktop/
Notebook designs using the VIA MVP3 style chipset. It
provides all necessary clock signals for such a system.
Spread spectrum may be enabled through I2C programming.
Spread spectrum typically reduces system EMI by 8dB to
10dB. This simplifies EMI qualification without resorting to
board design iterations or costly shielding. The ICS9148-58
employs a proprietary closed loop design, which tightly
controls the percentage of spreading over process and
temperature variations.
Serial programming I²C interface allows changing functions,
stop clock programming and frequency selection. The SD_SEL
latched input allows the SDRAM frequency to follow the
CPUCLK frequency(SD_SEL=1) or the AGP clock
frequency(SD_SEL=0)
Block Diagram
Features
• Generates the following system clocks:
- 4 CPU(2.5V/3.3V) upto 100MHz.
- 6 PCI(3.3V) @ 33.3MHz
- 2AGP(3.3V) @ 2 x PCI
- 12 SDRAMs(3.3V) @ either CPU or AGP
- 2 REF (3.3V) @ 14.318MHz
• Skew characteristics:
- CPU – CPU<250ps
- SDRAM – SDRAM < 250ps
- CPU – SDRAM < 250ps
- CPU(early) – PCI : 1-4ns
• Spread Spectrum 0 to -5% down spread.
• Serial I²C interface for Power Management, Frequency
Select, Spread Spectrum.
• Efficient Power management scheme through PCI and CPU
STOP CLOCKS.
• Uses external 14.318MHz crystal
• 48 pin 300mil SSOP.
Pin Configuration
Power Groups
VDD1 = REF (0:1), X1, X2
VDD2 = PCICLK_F, PCICLK(0:5)
VDD3 = SDRAM (0:11), supply for PLL core,
24 MHz, 48MHz
VDD4 = AGP (0:1)
VDDL = CPUCLK (0:3)
9148-58 Rev C 12/07/98
48-Pin SSOP
* Internal Pull-up Resistor of
240K to 3.3V on indicated inputs
Pentium is a trademark of Intel Corporation
I²C is a trademark of Philips 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.