DC-DC converter

A DC-DC converter to control an output voltage comprising:

• a switching transistor including a first terminal connected to a power input terminal;
• an inductor including a first end connected to a second terminal of the switching transistor and a second end connected to an output terminal;
• a synchronous rectification transistor including a first terminal connected to a junction node between the switching transistor and the inductor and a second terminal connected to a ground terminal;
• a first voltage detector to detect whether or not a voltage of a junction node between the switching transistor and the inductor is higher than a first voltage;
• a second voltage detector to detect whether or not a voltage of the junction node between the switching transistor and the inductor is higher than a second voltage that is higher than the first voltage and is a positive voltage;
• and
• a selection mechanism to select one of the first voltage detector and the second voltage detector in accordance with a control signal,
• wherein the synchronous rectification transistor is turned off with an output signal from one of the first voltage detector and the second voltage detector that is selected.

A DC-DC converter to control an output voltage, comprising:

• a switching transistor including a first terminal connected to a power input terminal;
• an inductor including a first end connected to a second terminal of the switching transistor and a second end connected to an output terminal;
• a synchronous rectification transistor including a first terminal connected to a junction node between the switching transistor and the inductor and a second terminal connected to a ground terminal;
• a current-voltage converting device to convert an electric current flowing through the synchronous rectification transistor into a voltage;
• a first reference voltage output mechanism to output a first reference voltage that is 0 V or near 0 V;
• a second reference voltage output mechanism to output a second reference voltage that is higher than the first reference voltage and is positive;
• a selection mechanism to receive both the first reference voltage and the second reference voltage and output one of the first reference voltage and the second reference voltage in accordance with a control signal;
• and
• a comparator to compare the output voltage from the current-voltage converting device with the first reference voltage or the second reference voltage outputted from the selection mechanism,
• the comparator outputting a signal to turn off the synchronous rectification transistor when detecting that the output voltage from the current-voltage converting device is not lower than the first reference voltage or the second reference voltage selected by the selection mechanism.