System restart circuit and system restart method thereof

A system restart circuit, comprising:

• a capacitive element, a first end of which is coupled to a first voltage level;
• a restart switch, coupled to a second end of the capacitive element and the first voltage level respectively, for selectively coupling the second end of the capacitive element to the first voltage level;
• and
• a first circuit, coupled to a second voltage level, the second end of the capacitive element and a system power supplying circuit, for establishing a current path between the second voltage level and the capacitive element during a restart time;
• wherein a voltage level of an enabling signal of the system power supplying circuit in an output node of the first circuit is set according to the voltage level of the second end of the capacitive element, and the voltage level of the second end of the capacitive element is determined by charging or discharging the capacitive element;
• and the system power supplying circuit will generate an output unless the voltage level of the enabling signal reaches a predetermined value.