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MPC8270VVB

PowerQUICC II Family Hardware Specifications

Freescale Semiconductor 

Clock Configuration Modes

Table 17. SoC Clocking Modes

Pins

PCI_MODE PCI_CFG[0] PCI_MODCK1

Clocking Mode

PCI Clock

Frequency Range

(MHZ)

Reference

1

—

—

Local bus

—

Table 18

0

0

0

PCI host

50–66

Table 19

0

0

1

25–50

Table 20

0

1

0

PCI agent

50–66

Table 21

0

1

1

25–50

Table 22

1 Determines PCI clock frequency range. See Section 7.2, “PCI Host Mode,” and Section 7.3, “PCI Agent Mode.”

Within each mode, the configuration of bus, core, PCI, and CPM frequencies is determined by seven bits

during the power-on reset—three hardware configuration pins (MODCK[1–3]) and four bits from

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 Local Bus Mode

This table lists clock configurations for the SoC in local bus mode. The frequencies 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

Clock configurations change only after PORESET is asserted.

Table 18. Clock Configurations for Local Bus Mode1

Mode2

Bus Clock3

(MHz)

MODCK_H-MODCK[1:3] Low High

CPM

Multiplication

Factor4

CPM Clock

(MHz)

Low

High

CPU

Multiplication

Factor5

CPU Clock

(MHz)

Low

High

0000_000

0000_001

0000_010

0000_011

0000_100

0000_101

0000_110

0000_111

Default Modes (MODCK_H= 0000)

37.5 133.3

3

112.5 400.0

4

150.0 533.3

33.3 133.3

3

100.0 400.0

5

166.7 666.7

37.5 100.0

4

150.0 400.0

4

150.0 400.0

30.0 100.0

4

120.0 400.0

5

150.0 500.0

60.0 167.0

2

120.0 334.0

2.5

150.0 417.5

50.0 167.0

2

100.0 334.0

3

150.0 501.0

60.0 160.0

2.5

150.0 400.0

2.5

150.0 400.0

50.0 160.0

2.5

125.0 400.0

3

150.0 480.0

Full Configuration Modes

0001_000

50.0 167.0

2

100.0 334.0

4

200.0 668.0

MPC8280 PowerQUICC II Family Hardware Specifications, Rev. 2

Freescale Semiconductor

27

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