ICS9248-127 Datasheet, PDF (1/14 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for PENTIUM/ProTM

Integrated
Circuit
Systems, Inc.
ICS9248 - 127
Frequency Generator & Integrated Buffers for PENTIUM/Pro^TM
General Description
The ICS9248-127 is the single chip clock solution for Desktop
designs using the VIA MVP4 and Aladdin 7 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-
127 employs a proprietary closed loop design, which tightly
controls the percentage of spreading over process and
temperature variations.
Features
• Up to 124MHz frequency support.
• Spread Spectrum for EMI control 0 to -0.5% down
spread and ±0.25% center spread
• Serial I²C interface for Power Management,
Frequency Select, Spread Spectrum.
• Provides the following system clocks
- 4-CPUs @ 3.3V, up to 124MHz.
- 13-SDRAMs @3.3V, up to 124MHz
(including SDRAM_F)
- 6-PCI (including 1 free running, PCICLK_F)
@3.3V, CPU/2 or CPU/3.
- 1-24MHz @3.3V fixed.
- 1-48MHz @3.3V fixed.
- 2-REF @3.3V, 14.318MHz.
• Efficient Power management scheme through PCI
and STOP CLOCKS.
Block Diagram
X1
X2
BUFFER IN
PLL2
/2
XTAL
OSC
FS(3:0)
4
MODE
CLK_STOP#
PCI_STOP#
SDATA
SCLK
PLL1
Spread
Spectrum
LATCH
4
POR
Control
Logic
Config.
Reg.
STOP
STOP
PCI
CLOCK
DIVDER
STOP
48MHz
24MHz
2 ^{REF (1:0)}
CPUCLK_F
3 ^{CPUCLK (2:0)}
12 ^{SDRAM (11:0)}
SDRAM_F
PCICLK (4:0)
5
PCICLK_F
Pin Configuration
VDDREF
1
*PCI_STOP#/REF0
2
GND
3
X1
4
X2
5
VDDPCI
6
*MODE/PCICLK_F
7
*FS3/PCICLK0
8
GND
9
PCICLK1
10
PCICLK2
11
PCICLK3
12
PCICLK4
13
VDDPCI
14
BUFFER IN
15
GND
16
SDRAM11
17
SDRAM10
18
VDDSDR
19
SDRAM9
20
SDRAM8
21
GND
22
SDATA
23
SCLK
24
48
REF1/FS2*
47
VDDCPU
46
CPUCLK_F
45
CPUCLK0
44
GND
43
CPUCLK1
42
CPUCLK2
41
CLK_STOP#
40
GND
39
SDRAM_F
38
SDRAM0
37
SDRAM1
36
VDDSDR
35
SDRAM2
34
SDRAM3
33
GND
32
SDRAM4
31
SDRAM5
30
VDDSDR
29
SDRAM6
28
SDRAM7
27
VDD48
26
48MHz/FS0*
25
24MHz/FS1*
48-Pin SSOP
* Internal Pull-up Resistor of 240K to VDD
Power Groups
VDDCPU, GNDCPU = CPUCLKS, CPUCLK_F
VDDSDR, GNDSDR = SDRAMCLKS, SDRAM_F
VDDPCI, GNDPCI = PCICLKS, PCICLK_F
VDD48 = 48MHz, 24MHz
VDDREF, GNDREF = REF, X1, X2
9248-127 Rev C 8/18/00
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.