Freescale Semiconductor MCF54455 Reference Manual page 181

Clock Module
FB_AD[2:0]
BOOTMOD = 10)
Clock Module
XTAL
EXTAL
FB_AD3 (when
BOOTMOD = 10)
XTAL32K
EXTAL32K
SSICLKIN
USBCLKIN
Notes:
1
For the 256MAPBGA devices, FB_AD[1:0] control the multiplier during reset.
2 The output frequency of OUTDIV2 must equal the output frequency of OUTDIV1  2.
The output frequency of OUTDIV3 must equal the output frequency of OUTDIV1  4 or OUTDIV  8.
3
4
The output frequency of OUTDIV5 must be 60MHz if it is used as the USB clock source.
5
The SDRAMC, FECs, and PCI modules are disabled in limp mode. The USB controller is essentially
disabled, as well. However, it is able to capture a wake-up event to bring the device out of limp mode.
6
The SDRAMC, SSI, USB, and real time clock contain some logic that uses the f
to the module-specific clock.
7
When loading boot code via the SBF, the device is clocked by the main oscillator (f
8-2
1
when
FB_AD4 (when
BOOTMODE = 10) or
MISCCR[LIMP]
PCR
OUTDIV1
f
vco
PCR
OUTDIV2
[PFDR]
OUTDIV3
f
ref
OUTDIV4
OUTDIV5
2
CDR[LPDIV]
Serial Boot
Facility
Figure 8-1. Device Clock Connections
0 f
sys
1
f
sys/2
f
sys/(4 or 8)
MISCCR[SSISRC]
MISCCR[USBSRC]
clock, in addition
sys/2
).
ref
V4 ColdFire Core
SRAM/Cache
BDM
CAU
SD_CLK
SDRAMC
SD_CLK
FlexBus FB_CLK
PCI
eDMA
FECn_TXCLK
FECs
FECn_RXCLK
PIT
DMA Timers
DSPI DSPI_SCK
UART
I2C
GPIO
RNG
ATA
SSI
USB OTG
Real Time Clock
Freescale Semiconductor