Circuit for switching power supply and switching power supply device

A circuit operable to switch a power supply and forma power supply switching device that is operable to generate an output voltage based on an input voltage, the circuit comprising:

• an input terminal operable to receive the input voltage;
• a switch terminal;
• a ground terminal
• a high-side transistor disposed between the input terminal and the switch terminal;
• a low-side transistor disposed between the switch terminal and the ground terminal;
• a gate driver operable to drive each gate of the high-side transistor and the low-side transistor;
• a control circuit operable to use the gate driver to perform a feedback control to turn on or off the high-side transistor and the low-side transistor based on a feedback voltage corresponding to the output voltage;
• and
• a protection circuit operable to perform a protection operation for turning on the high-side transistor or the low-side transistor regardless of the feedback control
• based on a switch voltage at the switch terminal and the input voltage,
• based on a backflow current from the ground terminal to the switch terminal, or
• based on the input voltage and a predetermined determination voltage,
• wherein the protection circuit is operable to detect the backflow current in a shutdown state in which the feedback control is stopped, and perform the protection operation of turning on the low-side transistor based on a detection result of the backflow current.

A circuit operable to switch a power supply and forma power supply switching device that is operable to generate an output voltage based on an input voltage, the circuit comprising:

• an input terminal operable to receive the input voltage;
• a switch terminal;
• a ground terminal;
• a high-side transistor disposed between the input terminal and the switch terminal;
• a low-side transistor disposed between the switch terminal and the ground terminal;
• a gate driver operable to drive each gate of the high-side transistor and the low-side transistor;
• a control circuit operable to use the gate driver to perform a feedback control to turn on or off the high-side transistor and the low-side transistor based on a feedback voltage corresponding to the output voltage;
• an undervoltage-lockout (UVLO) detection circuit operable to output a predetermined UVLO signal when the input voltage drops below the predetermined determination voltage;
• and
• a protection circuit operable to perform a protection operation for turning on the high-side transistor or the low-side transistor regardless of the feedback control
• based on a switch voltage at the switch terminal and the input voltage,
• based on a backflow current from the ground terminal to the switch terminal, or
• based on the input voltage and a predetermined determination voltage,
• wherein the protection circuit is operable to receive an output of the predetermined UVLO signal and performs the protection operation.