Switching power supply, control circuit for controlling switching power supply, control method of switching power supply and module substrate

A switching power supply comprising:

• a first switch provided between a positive terminal of a DC power supply and a positive terminal of a load;
• a first capacitor provided between a second switch and a node of the first switch on a DC power supply side;
• the second switch connected in series with the first switch, the first switch connected in parallel with the first capacitor and a second switch;
• a first inductor provided between the first capacitor and the positive terminal of the DC power supply;
• and
• a control circuit that turns off the second switch after the first switch is turned off and when or before a voltage across the first capacitor becomes zero,
• wherein the control circuit:
• turns off the second switch in a case where a voltage difference between both ends of the first capacitor is equal to or smaller than a predetermined value and a signal for turning on/off the second switch indicates off;
• and
• turns on the second switch in at least one of a case where the potential difference between both the ends of the first capacitor is greater than the predetermined value and a case where the signal for turning on/off the second switch indicates off.

A switching power supply comprising:

• a first switch provided between a positive terminal of a DC power supply and a positive terminal of a load;
• a first capacitor provided between a second switch and a node of the first switch on a DC power supply side;
• the second switch connected in series with the first switch, the first switch connected in parallel with the first capacitor and a second switch;
• a first inductor provided between the first capacitor and the positive terminal of the DC power supply;
• and
• a control circuit that turns off the second switch after the first switch is turned off and when or before a voltage across the first capacitor becomes zero,
• wherein the control circuit:
• turns on the second switch when a signal for turning on/off the second switch is turned on from off;
• and
• turns off the second switch when an absolute value of a current that flows through the first capacitor becomes equal to or greater than a predetermined value.

A module substrate comprising

• a single substrate;
• and
• a switching power supply formed on the single substrate,
• the switching power supply including
• a first switch provided between a positive terminal of a DC power supply and a positive terminal of a load;
• a first capacitor provided between a second switch and a node of the first switch on a DC power supply side;
• the second switch connected in series with the first switch, the first switch connected in parallel with the first capacitor and the second switch;
• a first inductor provided between the first capacitor and the positive terminal of the DC power supply;
• a diode connected in parallel with a second switch so that a cathode of the diode is located on the DC power supply side and is connected to a node between the second switch and the first capacitor, and an anode thereof is located on a load side;
• a second capacitor being provided between a node of the first inductor on the DC power supply side and a negative terminal of the DC power supply and storing a charge stored in the first capacitor;
• and
• a control circuit that turns off the second switch after the first switch is turned off and when or before a voltage across the first capacitor becomes zero.

A module substrate comprising:

• a switching power supply;
• and
• an electronic component supplied with power from the switching power supply,
• the switching power supply including:
• a first switch provided between a positive terminal of a DC power supply and a positive terminal of a load;
• a first capacitor provided between a second switch and a node of the first switch on a DC power supply side;
• the second switch connected in series with the first switch, the first switch connected in parallel with the first capacitor and the second switch;
• a first inductor provided between the first capacitor and the positive terminal of the DC power supply;
• a diode connected in parallel with a second switch so that a cathode of the diode is located on the DC power supply side and is connected to a node between the second switch and the first capacitor, and an anode thereof is located on a load side;
• a second capacitor being provided between a node of the first inductor on the DC power supply side and a negative terminal of the DC power supply and storing a charge stored in the first capacitor;
• and
• a control circuit that turns off the second switch after the first switch is turned off and when or before a voltage across the first capacitor becomes zero.