
3
ICS9248-195
0375D—02/02/04
Byte0: Functionality and Frequency Select Register (default = 0)
Serial Configuration Command Bitmap
Notes:
1, Default at Power-up will be for latched logic inputs to define frequency. Bit [2, 6:4] are default to 0011.
2, PWD = Power-Up Default
The
ICS9248-195
is the single chip clock solution for Notebook designs using the 440BX, MX, VIA PM/PL/PLE 133
style chip set, with Coppermine or Tualatin processor, for Note book applications. It provides all necessary clock signals
for such a system.
Spread spectrum may be enabled through I
2
C 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-
195
employs a proprietary closed loop design, which tightly controls the percentage of spreading over process and
temperature variations.
General Description
Bit
PWD
FS3
Bit2
FS2
Bit6
FS1
Bit5
FS0
Bit4
CPUCLK
PCICLK
Center
Spread %
Down
Spread%
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
66.67
100.00
66.67
133.33
66.67
100.00
100.00
133.33
66.67
100.00
90.00
133.33
70.00
105.00
133.33
140.00
33.33
33.33
33.33
33.33
33.33
33.33
33.33
33.33
33.33
33.33
30.00
33.33
35.00
35.00
33.33
35.00
±0.35%
±0.35%
±0.60%
±0.35%
±0.23%
±0.23%
±0.60%
±0.23%
±0.45%
±0.45%
±0.35%
±0.45%
±0.35%
±0.35%
±0.60%
±0.35%
-0.70%
-0.70%
-1.20%
-0.70%
-0.45%
-0.45%
-1.20%
-0.45%
-0.90%
-0.90%
-0.70%
-0.90%
-0.70%
-0.70%
-1.20%
-0.70%
0 - Normal
1 - Spread Spectrum Enabled
Note1
0011
Description
1
0
1
0 = Center Spread Spectrum Modulation
1 = Down Spread Spectrum Modulation
0 - Frequency is selected by hardware select pins. Latched inputs.
1 - Frequency is controlled by I
2
C programming.
0 - Running
1 - Tristate all outputs
0
Bit 0
Bit 7
Bit 3
Bit 2,
6:4
Bit 1