MPC8272 PowerQUICC II Family Hardware Specifications, Rev. 1.5
Freescale Semiconductor
33
Clock Configuration Modes
7.2
PCI Agent Mode
Table 18 and
Table 19 show configurations for PCI agent mode. The frequency values listed 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. Note that in PCI agent mode the
input clock is PCI clock.
1110_100
50.0
100.0
3
150.0 300.0
5.5
275.0 550.0
6
25.0
50.0
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 16 for higher 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
Table 18. Clock Configurations for PCI Agent Mode (PCI_MODCK=0) 1, 2
Mode 3
PCI Clock
(MHz)
CPM
Multiplication
Factor 4
CPM Clock
(MHz)
CPU
Multiplication
Factor 5
CPU Clock
(MHz)
Bus
Division
Factor
Bus Clock
(MHz)
MODCK_H-
MODCK[1-3]
Low
High
Low
High
Low
High
Low
High
Default Modes (MODCK_H=0000)
0000_000
60.0
66.7
2
120.0 133.3
2.5
150.0 166.7
2
60.0
66.7
0000_001
50.0
66.7
2
100.0 133.3
3
150.0 200.0
2
50.0
66.7
0000_010
50.0
66.7
3
150.0 200.0
3
150.0 200.0
3
50.0
66.7
0000_011
50.0
66.7
3
150.0 200.0
4
200.0 266.6
3
50.0
66.7
0000_100
50.0
66.7
3
150.0 200.0
3
180.0 240.0
2.5
60.0
80.0
0000_101
50.0
66.7
3
150.0 200.0
3.5
210.0 280.0
2.5
60.0
80.0
0000_110
50.0
66.7
4
200.0 266.6
3.5
233.3 311.1
3
66.7
88.9
Table 17. Clock Configurations for PCI Host Mode (PCI_MODCK=1) 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
(MHz)
MODCK_H-
MODCK[1-3]
Low
High
Low
High
Low
High
Low
High