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Freescale Semiconductor
8-1
Chapter 8
Clock Module
8.1
Introduction
The clock module allows the device to be configured for one of several clocking methods. Clocking modes
include internal phase-locked loop (PLL) clocking with an external clock reference or an external crystal
reference supported by an internal crystal amplifier. The PLL can also be disabled, and an external
oscillator can directly clock the device. The clock module contains:
•
Crystal amplifier and oscillator (OSC)
•
Phase-locked loop (PLL)
•
Status and control registers
•
Control logic
NOTE
Throughout this manual, f
sys
refers to the core frequency and f
sys/2
refers to
the internal bus frequency.
is a high-level representation of clock connections. The exact functionality of the blocks is not
illustrated (SBF controls many configuration options, clocks to the SDRAMC, USB, FECs, PCI, and ATA
controllers are disabled when the device is in limp mode, and the clocks to individual modules may be
disabled via the peripheral power management registers as described in
).
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...