Information

Clock name Description
Bus clock MCGOUTCLK divided by OUTDIV2 clocks the bus slaves
and peripheral (excluding memories)
FlexBus clock MCGOUTCLK divided by OUTDIV3 clocks the external
FlexBus interface
Flash clock MCGOUTCLK divided by OUTDIV4 clocks the flash memory
MCGIRCLK MCG output of the slow or fast internal reference clock
MCGFFCLK MCG output of the slow internal reference clock or a divided
MCG external reference clock. The MCGFFCLK is further
divided by 2 before being made available to modules outside
the MCG (as shown in the preceding figure).
MCGOUTCLK MCG output of either IRC, MCGFLLCLK, MCGPLLCLK, or
MCG's external reference clock that sources the core,
system, bus, FlexBus, and flash clock. It is also an option for
the debug trace clock.
MCGFLLCLK MCG output of the FLL. MCGFLLCLK or MCGPLLCLK may
clock some modules.
MCGPLLCLK MCG output of the PLL. MCGFLLCLK or MCGPLLCLK may
clock some modules.
MCG external reference clock Input clock to the MCG sourced by the system oscillator
(OSCCLK) or RTC oscillator
OSCCLK System oscillator output of the internal oscillator or sourced
directly from EXTAL
OSCERCLK System oscillator output sourced from OSCCLKthat may
clock some on-chip modules
OSC32KCLK System oscillator 32kHz output
ERCLK32K Clock source for some modules that is chosen as
OSC32KCLK or the RTC clock
RTC clock RTC oscillator output for the RTC module
LPO PMC 1kHz output
5.4.1 Device clock summary
The following table provides more information regarding the on-chip clocks.
Table 5-1. Clock Summary
Clock name Run mode
clock frequency
VLPR mode
clock frequency
Clock source Clock is disabled
when…
MCGOUTCLK Up to 100 MHz Up to 2 MHz MCG In all stop modes
Core clock Up to 100 MHz Up to 2 MHz MCGOUTCLK clock
divider
In all wait and stop
modes
System clock Up to 100 MHz Up to 2 MHz MCGOUTCLK clock
divider
In all stop modes
Bus clock Up to 50 MHz Up to 2 MHz MCGOUTCLK clock
divider
In all stop modes
Table continues on the next page...
Chapter 5 Clock Distribution
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 169