Micro controller with low noise clock generator and System having the same

摘要

PURPOSE: A microcontroller equipping with a low noise embedded clock generator and a system installing the same are provided to share a clock output pin with the pin used for other use while reducing the noise due to a clock source applied from the outside of the microcontroller. CONSTITUTION: The input pin(XTAL_in) receives an input signal from the outside of the microcontroller. The first clock generator(200) generates the clock by the full-swing amplification of the signal from the input pin(XTAL_in). An output pin(XTAL_out) outputs an output signal from the first clock generator(200). The first switch(400) transfers an internal signal of the microcontroller to the output pin(XTAL_out) when the microcontroller is operated on an MDS(Microcontroller Development System) mode. The second switch(300) between an output node and the output pin(XTAL_out), adjusts the current flowing to the output pin(XTAL_out) from the output node of the first clock generator(200) when the first clock generator(200) is a clock generation mode, and is disabled on the MDS mode. A control register(500) selectively turns on/off the switches(300a-300n) of the first and the second switch(400,300).