ICS9248-126 Datasheet, PDF (2/12 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for Celeron & PII/III™ & K6

ICS9248-126
General Description
The ICS9248-126 is the single chip clock solution for
Desktop/Notebook designs using the SIS 540/630 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 ICS9248-126
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.
Power Groups
VDDREF = REF, X1, X2
VDDPCI = PCICLK_F, PCICLK
VDDSDR = SDRAM, supply for PLL core,
VDD48 = 48MHz, 24MHz
VDDLCPU = CPUCLKs
Pin Configuration
PIN NUMBER
1, 6, 15, 19, 27, 30,
36, 42
2
3, 10, 16, 22,
33, 39, 44
4
5
7
8
14, 13, 12, 11, 9
41, 40, 38, 37, 35,
34, 32, 31, 29, 28,
21, 20, 18, 17
23
24
25
26
43, 45, 46
47
48
PIN NAME
VDD
REF0
FS3
GND
X1
X2
FS1
P CIC LK 0
FS2
P CIC LK 1
PCICLK (6:2)
SDRAM (13:0)
SDATA
SCLK
CPU2.5_3.3#
24_48MHz
FS0
48MHz
CPUCLK (2:0)
VDDLCPU
REF1
TYPE
PWR
OUT
IN
PWR
IN
OUT
IN
OUT
IN
OUT
OUT
DESCRIPTION
3.3V Power supply for SDRAM output buffers, PCI output buffers,
reference output buffers and 48MHz output
14.318 MHz reference clock.
Frequency select pin.
Ground pin for 3V outputs.
Crystal input,nominally 14.318MHz.
Crystal output, nominally 14.318MHz.
Frequency select pin.
PCI clock outputs.
Frequency select pin.
PCI clock outputs.
PCI clock outputs.
OUT
SDRAM clock outputs
I/O
IN
IN
OUT
IN
OUT
OUT
PWR
OUT
Data pin for I²C circuitry 5V tolerant
Clock input of I2C input, 5V tolerant input
Voltage select 2.5V when high - 3.3V when low
Clock output for super I/O/USB default is 24MHz
Frequency select pin.
48MHz output clock
CPU clock outputs.
Power pin for the CPUCLKs. 2.5V
14.318 MHz reference clock.
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