MPC8248 Freescale Semiconductor, Inc, MPC8248 Datasheet - Page 25

• Manufacturer Part Number: MPC8248
• Description: Mpc8248 Powerquicc Ii Integrated Communications Processor
• Manufacturer: Freescale Semiconductor, Inc

hardware configuration word[28–31] (MODCK_H). Both the PLLs and the dividers are set according to
the selected clock operation mode as described in the following sections.
7.1
Table 16
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 host mode the
input clock is the bus clock.
Freescale Semiconductor
MODCK[1-3]
MODCK_H-
0000_000
0000_001
0000_010
0000_011
0000_100
0000_101
0000_110
0000_111
0001_000
0001_001
0001_010
0001_011
0010_000
0010_001
0010_010
Mode
and
PCI Host Mode
3
Table 17
Clock configurations change only after PORESET is asserted.
The minimum Tval = 2 ns when PCI_MODCK = 1, and the minimum
Tval = 1 ns when PCI_MODCK = 0. Therefore, designers should use clock
configurations that fit this condition to achieve PCI-compliant AC timing.
Table 16. Clock Configurations for PCI Host Mode (PCI_MODCK=0)
Low
60.0
50.0
60.0
60.0
60.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
Bus Clock
(MHz)
MPC8272 PowerQUICC II™ Family Hardware Specifications, Rev. 1.5
show configurations for PCI host mode. The frequency values listed are for the
High
66.7
66.7
80.0
80.0
80.0
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
Multiplication
Factor
CPM
2.5
2.5
2.5
3.5
2
2
3
3
3
3
3
3
4
4
4
Default Modes (MODCK_H=0000)
4
NOTE: Tval (Output Hold)
Full Configuration Modes
120.0 133.3
100.0 133.3
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
150.0 200.0
200.0 266.6
200.0 266.6
200.0 266.6
CPM Clock
Low
(MHz)
NOTE
High
Multiplication
Factor
CPU
2.5
3.5
3.5
3
3
4
3
4
5
6
7
8
5
6
7
5
150.0 166.7
150.0 200.0
180.0 240.0
210.0 280.0
240.0 320.0
150.0 200.0
175.0 233.3
200.0 266.6
250.0 333.3
300.0 400.0
350.0 466.6
400.0 533.3
250.0 333.3
300.0 400.0
350.0 466.6
CPU Clock
Low
(MHz)
High
Division
Factor
PCI
Clock Configuration Modes
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
1, 2
Low
60.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
PCI Clock
(MHz)
High
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
66.7
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