
MPC8272 PowerQUICC II Family Hardware Specifications, Rev. 2
30
Freescale Semiconductor
Clock Configuration Modes
1100_000
Reserved
1100_001
Reserved
1100_010
Reserved
1
The “l(fā)ow” values are the minimum allowable frequencies for a given clock mode. The minimum bus frequency in a
table entry guarantees only the required minimum CPU operating frequency. The “high” values are for the purpose
of illustration only. Users must select a mode and input bus frequency so that the resulting configuration does not
exceed the frequency rating of the user’s device. The minimum CPU frequency is 150 MHz for commercial
temperature devices and 175 MHz for extended temperature devices. The minimum CPM frequency is 120 MHz.
2
PCI_MODCK determines the PCI clock frequency range. Refer to
Table 17 for lower range configurations.
3
MODCK_H = hard reset configuration word [28–31] (refer to Section 5.4 in the
MPC8260 User’s Manual).
MODCK[1-3] = three hardware configuration pins.
4
CPM multiplication factor = CPM clock/bus clock
5
CPU multiplication factor = Core PLL multiplication factor
6
CPM_CLK/PCI_CLK ratio. When PCI_MODCK = 0, the ratio of CPM_CLK/PCI_CLK should be calculated from
SCCR[PCIDF] as follows:
CPM_CLK/PCI_CLK = (PCIDF + 1) / 2.
Table 17. Clock Configurations for PCI Host Mode (PCI_MODCK=1) 1, 2
Mode 3
Bus Clock
(MHz)
CPM
Multiplication
Factor 4
CPM Clock
(MHz)
CPU
Multiplication
Factor 5
CPU Clock
(MHz)
PCI
Division
Factor 6
PCI Clock
(MHz)
MODCK_H-
MODCK[1-3]
Low
High
Low
High
Low
High
Low
High
Default Modes (MODCK_H=0000)
0000_000
60.0
100.0
2
120.0 200.0
2.5
150.0 250.0
4
30.0
50.0
0000_001
50.0
100.0
2
100.0 200.0
3
150.0 300.0
4
25.0
50.0
0000_010
60.0
120.0
2.5
150.0 300.0
3
180.0 360.0
6
25.0
50.0
0000_011
60.0
120.0
2.5
150.0 300.0
3.5
210.0 420.0
6
25.0
50.0
0000_100
60.0
120.0
2.5
150.0 300.0
4
240.0 480.0
6
25.0
50.0
0000_101
50.0
100.0
3
150.0 300.0
3
150.0 300.0
6
25.0
50.0
0000_110
50.0
100.0
3
150.0 300.0
3.5
175.0 350.0
6
25.0
50.0
0000_111
50.0
100.0
3
150.0 300.0
4
200.0 400.0
6
25.0
50.0
Full Configuration Modes
0001_000
50.0
100.0
3
150.0 300.0
5
250.0 500.0
6
25.0
50.0
0001_001
50.0
100.0
3
150.0 300.0
6
300.0 600.0
6
25.0
50.0
Table 16. Clock Configurations for PCI Host Mode (PCI_MODCK=0) 1, 2 (continued)
Mode 3
Bus Clock
(MHz)
CPM
Multiplication
Factor 4
CPM Clock
(MHz)
CPU
Multiplication
Factor 5
CPU Clock
(MHz)
PCI
Division
Factor 6
PCI Clock
(MHz)
MODCK_H-
MODCK[1-3]
Low
High
Low
High
Low
High
Low
High