USB 48MHz
USB_CLKIN
SIM_CLKDIV2
[USBFRAC, USBDIV]
SIM_SOPT2[USBSRC]
MCGPLLCLK
SIM_SOPT2[PLLFLLSEL]
MCGFLLCLK
IRC48MCLK
Figure 5-7. USB 48 MHz clock source
NOTE
The MCGFLLCLK does not meet the USB jitter specifications
for certification. The IRC48MCLK is only usable as a USB
clock source in USB Device operation with the USB Clock
Recover function enabled.
5.7.9 UART clocking
UART0 and UART1 modules operate from the core/system clock, which provides higher
performance level for these modules. All other UART modules operate from the bus
clock.
5.7.10 LPUART0 clocking
The LPUART0 module has a selectable clock as shown in the following figure.
NOTE
The chosen clock must remain enabled if the LPUART0 is to
continue operating in all required low-power modes.
Chapter 5 Clock Distribution
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc.
161
