Switching power supply

A switching power supply comprising:

• an inductor connected to an input voltage terminal;
• a first switch configured to form a first electrical path between the inductor and an output voltage terminal;
• a second switch configured to form a second electrical path between the inductor and a ground voltage terminal;
• a third switch configured to electrically connect both terminals of the inductor;
• a negative current sensor configured to sense an inductor current flowing through the first electrical path, and generate an over-current protection signal when the inductor current is sensed as a negative current equal to or more than a preset value;
• and
• a controller configured to enable a DCM when the over-current protection signal is generated, and turn off the first and second switches and turn on the third switch, in response to the enabled DCM.

A switching power supply comprising:

• an inductor connected to an input voltage terminal;
• a first switch configured to form a first electrical path between the inductor and an output voltage terminal;
• a second switch configured to form a second electrical path between the inductor and a ground voltage terminal;
• a third switch configured to electrically connect both terminals of the inductor;
• a negative current sensor configured to sense an inductor current flowing through the first electrical path, and generate an over-current protection signal when the inductor current is sensed as a negative current equal to or more than a preset value;
• and
• a controller configured to turn off the first switch when the over-current protection signal is generated, control the second switch to maintain an on-state until the inductor current reaches the zero current, and turn off the second switch and turn on the third switch when the inductor current reaches the zero current.