+/+…when timing is critical
C9819
133 MHz I2C Clock Generator for Mobile Pentium®III / Rambus Systems
Preliminary
Frequency Extension
Frequency Extension is a feature in this device that allows the user to expand on the clock frequency originally selected
following table 1, page1.
This feature provides the user two additional selection lines FE1 and FE0 that are used to select the desired percentage
of frequency extension.
These signals are bi-directional strapping pins and are latched into the device at power up, as described on page 3.
This feature does not effect the frequency of the 48MHz and REF(0:2) clocks, therefore, 48MHz and REF(0:2)
frequencies remain the same regardless of the status of FE(0:1) and Sel133/100#.
For default frequencies (100MHz or 133.3MHz) these signals should be connect high through a 10KΩ resistor to
VDD.
For extension option see table 5 below.
When the frequency extension is applied Spread Spectrum is not applicable.
Frequency Extension Table (MHz)
Sel133/100# FE
FE0
0
1
0
1
0
1
0
CPU
120
110
105
100
160
146.67
140
133.3
CPU/2
60
55
52.5
50
80
73.33
70
3V66(0:2) PCI(F,0:6)
IOAPIC(0:1)
20
Function
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
80
73.33
70
40
36.67
35
20 % extension to 100 MHz
10 % extension to 100 MHz
5 % extension to 100 MHz
0 %, DEFAULT, 100 MHz
20 % extension to 133.3 MHz
10 % extension to 133.3 MHz
5 % extension to 133.3 MHz
0 %, DEFAULT, 133.3 MHz
18.33
17.5
16.67
20
18.33
17.5
16.67
66.6
80
33.3
40
73.33
70
36.67
35
1
66.6
66.6
33.3
Table 5.
INTERNATIONAL MICROCIRCUITS, INC 525 LOS COCHES ST.
MILPITAS, CA 95035, USA TEL: 408-263-6300 FAX 408-263-6571
Rev 1.0
11/1/1999
Page 9 of 17
http://www.imicorp.com
CYPRESS [ CYPRESS ]
