DC-DC converter, power supply circuit, method for controlling DC-DC converter, and method for controlling power supply circuit

A power supply circuit comprising:

• a DC-DC converter for receiving a power supply voltage and generating a first output voltage, wherein the DC-DC converter includes;
• a voltage generation circuit having a first output transistor, wherein the first output transistor performs switching, and the voltage generating circuit generates the first output voltage in accordance with the switching of the first output transistor;
• and
• a switching control circuit connected to the voltage generation circuit for controlling the switching of the first output transistor;
• a voltage regulator connected to the DC-DC converter for generating the second output voltage in accordance with the first output voltage;
• a current detection circuit for detecting a load current derived from the second output voltage of the voltage generation circuit to generate a first detection signal in accordance with the detected load current;
• and
• a stop control circuit connected to the voltage generation circuit, the switching control circuit, and the current detection circuit for maintaining the output transistor in an activated state and stopping the operation of the switching control circuit in accordance with the first detection signal when the load current is less than or equal to a predetermined value.

A method for controlling a DC-DC converter, wherein the DC-DC converter includes an output transistor for performing switching to generate an output voltage and a switching control circuit connected to the voltage generation circuit for controlling the switching of the output transistor, the method comprising the steps of:

• supplying a load with a load current derived from the output voltage of the output transistor;
• detecting the load current;
• determining whether the load current is less than or equal to a predetermined value;
• maintaining the output transistor in an activated state when the load current is determined as being less than or equal to the predetermined value;
• and
• stopping the operation of the switching control circuit when the load current is determined as being less than or equal to the predetermined value.

A method for controlling a power supply circuit, wherein the power supply circuit includes a DC-DC converter having an output transistor for performing switching to generate a first output voltage and a switching control circuit for controlling the switching of the output transistor, and a voltage regulator connected to the DC-DC converter for generating a second output voltage in accordance with the first output voltage, the method comprising the steps of:

• supplying a load with a load current derived from the second output voltage;
• detecting the load current;
• determining whether the load current is less than or equal to a predetermined value;
• maintaining the output transistor in an activated state when the load current is determined as being less than or equal to the predetermined value;
• and
• stopping the operation of the switching control circuit when the load current is determined as being less than or equal to the predetermined value.

A DC-DC converter comprising:

• a voltage generation circuit for receiving a power supply voltage and generating an output voltage, wherein the voltage generation circuit includes an output transistor for performing switching to generate the output voltage;
• a switching control circuit connected to the voltage generation circuit for controlling the switching of the output transistor;
• a current detection circuit connected to the voltage generation circuit for detecting a load current derived from the output voltage generation circuit to generate a detection signal;
• and
• a stop control circuit connected to the voltage generation circuit, the switching control circuit, and the current detection circuit for fixing the output transistor in an activated state and stopping the operation of the switching control circuit in accordance with the detection signal,
• wherein the switching control circuit switches between a first control performing PEM-control of the output transistor and a second control performing PWM-control of the output transistor in accordance with the detection signal.