Freescale Semiconductor MCF54455 Reference Manual page 186

Field
31–24 Feedback divider for setting the VCO frequency. Valid values range from 4 (0x4) to 34 (0x22). Other settings are
PFDR invalid and stable operation is not guaranteed. The reset value depends on the selected chip configuration. See
Chapter 11, "Chip Configuration Module (CCM),"
where f is the PLL input frequency from the internal oscillator or EXTAL clock source (defined by the selected
REF
chip configuration).
23–20 Reserved, must be cleared.
19–16 Output divider for generating the USB clock frequency. The divider is the value of this bit field plus 1. The reset value
OUTDIV5 depends on the selected chip configuration. See
information. A value of zero disables this clock.
Note: The OUTDIV5 resulting frequency must be 60 MHz if used as the USB clock source.
15–12 Output divider for generating the PCI clock frequency. The divider is the value of this bit field plus 1. The reset value
OUTDIV4 depends on the selected chip configuration. See
information. A value of zero disables this clock.
11–8 Output divider for generating the FlexBus clock (FB_CLK) frequency. The divider is the value of this bit field plus 1.
OUTDIV3 The reset value depends on the selected chip configuration. See
for more information. A value of zero disables this clock.
Note: The OUTDIV3 divider value must be four or eight times the OUTDIV1 divider. For example, if OUTDIV1 equals
0001, then OUTDIV3 must equal 0111 or 1111. FB_CLK must also not exceed 66 MHz.
Freescale Semiconductor
Table 8-3. PCR Field Descriptions
Description
for more information.

f = f PFDR
VCO REF
Chapter 11, "Chip Configuration Module (CCM),"
f
VCO
f =
------------------------------------ -
USB
OUTDIV5
Chapter 11, "Chip Configuration Module (CCM),"
f
VCO
f =
------------------------------------ -
PCI
OUTDIV4
f f
SYS
f = =
------------- - ------------------------------------ -
FB_CLK
4 or 8 OUTDIV3
+ 1
+ 1
Chapter 11, "Chip Configuration Module (CCM),"
VCO
+ 1
Clock Module
Eqn. 8-1
for more
Eqn. 8-2
for more
Eqn. 8-3
Eqn. 8-4
8-7