ICS9148-17 Datasheet, PDF (5/15 Pages) Integrated Circuit Systems – Frequency Generator & Integrated Buffers for PENTIUM/ProTM

ICS9148 - 17
Serial Configuration Command Bitmap
Byte0: Functionality and Frequency Select Register (default = 0)
Bit
Description
Bit 7
0 - ±1.5% Spread Spectrum Modulation
1 - ±0.6% Spread Spectrum Modulation
Bit 6,5,4 CPU Clock
PCI
AGP
PWD
0
Bit
6:4
Bit 3
Bit 2
Bit 1
Bit 0
111
100.2
33.4
66.8
110
90
30
60
101
83.3
32
64
100
75
32
64
011
75
37.5
75
010
68.5
34.25
68.5
001
66.8
33.4
66.8
000
60
30
60
0 - Frequency is selected by hardware select,
Latched Inputs
1 - Frequency is selected by Bit 6:4 (above)
0 - Spread Spectrum center spread type.
1 - Spread Spectrum down spread type.
0 - Normal
1 - Spread Spectrum Enabled
0 - Running
1- Tristate all outputs
Note 1
0,0,0
0
0
0
0
Note 1. Default at Power-up will be for latched logic inputs
to define frequency. Bits 4, 5, 6 are default to 000,
and if bit 3 is written to a 1 to use bits 6:4, then
these should be defined to desired frequency at same
write cycle.
Note: PWD = Power-Up Default
I²C is a trademark of Philips Corporation
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