M054LAN Datasheet, PDF (26/64 Pages) Nuvotem Talema – ARM Cortex™-M0 32-BIT MICROCONTROLLER

M052/M054 Data Sheet
6.3 Clock Controller
6.3.1 Overview
The clock controller generates the clocks for the whole chip, including system clocks and all
peripheral clocks. The clock controller also implements the power control function with the
individually clock ON/OFF control, clock source selection and a 4-bit clock divider. The chip will
not enter power-down mode until CPU sets the power down enable bit (PWR_DOWN_EN) and
Cortex-M0 core executes the WFI instruction. After that, chip enter power-down mode and wait for
wake-up interrupt source triggered to leave power-down mode. In the power down mode, the
clock controller turns off the external crystal and internal 22.1184 MHz oscillator to reduce the
overall system power consumption.
6.3.2 Clock Generator Block Diagram
The clock generator consists of 4 sources which list below:
z One external 4~24 MHz crystal
z One internal 22.1184 MHz RC oscillator
z One programmable PLL FOUT(PLL source consists of external 4~24 MHz crystal and
internal 22.1184M)
z One internal 10 kHz oscillator
XTL12M_EN(PWRCON[0])
XT_IN
External
Crystal
XT_OUT
4~24M
OSC22M_EN(PWRCON[2])
Internal ^22.1184M
OSC22M
OSC10K_EN(PWRCON[3])
10K
OSC10K
4~24M
PLL_SRC(PLLCON[19])
0
PLL
1
PLL FOUT
22.1184M
10K
Figure 6–3 Clock generator block diagram
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Publication Release Date: Mar 15, 2011
Revision V1.0