Table 7-3. Possible Clocking Ratios
for
Reference Clock
of
33.3MHz
Strapping Options Calculated Values (MHz)
FWD CPUlPLB FBK M
VCO CPU PLB
By-pass
2
1
x
- -
refclk refclk
2 x
-
-
refclk refclkl2
3 x
-
-
refclk refclkl3
4
x
- -
refclk refclkl4
3 1 4
12
400 133 133
3
2 2 12
400 133 66
3 2
3
18
600 200 100
3 2 4 24 800
266 133
3 3 2
18
600
200
66
3 4 1
12
400 133 33
3 4 2 24
800
266
66
4 1
3
12
400 100 100
4 1 4
16
533 133
133
4 2 2 16
533
133 66
4 2
3
24
800 200 100
4 3 1 12 400 100 33
4
3 2 24
800
200
66
4 4 1
16
533
133 33
6 1 2
12
400
66 66
6
1
3
18
600
100 100
6 1 4 24 800 133 133
6 2 1 12
400 66 33
6 2 2 24
800 133 66
6 3 1
18
600
100
33
6 4 1 24
800 133 33
Note 1: x = don't care.
Note 2: By-pass mode is for hardware emulator use
only.
Contact your IBM
representative for more information.
Note 3: Not all PPC405GP parts support the frequencies shown. Check
PPC405GP Datasheet for supported CPU and PLB frequencies for
a specific part number.
Preliminary Clocking
7-5