Information

25.3 Block Diagram
The OSC module uses a crystal or resonator to generate three filtered oscillator clock
signals. Three clocks are output from OSC module: OSCCLK for MCU system,
OSCERCLK for on-chip peripherals, and OSC32KCLK. The OSCCLK can only work in
run mode. OSCERCLK and OSC32KCLK can work in low power modes. For the clock
source assignments, refer to the clock distribution information of this MCU.
Refer to the chip configuration chapter for the external reference clock source in this
MCU.
The following figure shows the block diagram of the OSC module.
XTAL
EXTAL
XTL_CLK
CNT_DONE_4096
OSC_CLK_OUT
Mux
4096
Counter
OSC Clock Enable
STOP
OSC clock selection
OSCERCLK
ERCLKEN
OSCCLK
Range selections
Low Power config
OSC32KCLK
Oscillator Circuits
E N
Control and Decoding
logic
ERCLKEN
EREFSTEN
OSC_EN
Figure 25-1. OSC Module Block Diagram
25.4 OSC Signal Descriptions
The following table shows the user-accessible signals available for the OSC module.
Refer to signal multiplexing information for this MCU for more details.
Block Diagram
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
468 Freescale Semiconductor, Inc.