Power supply with reduced switching losses by blocking a feedback comparator's control signal

A power supply device comprising:

• an input terminal arranged to be connected to a direct-current (DC) power supply;
• a first switching element connected to the input terminal;
• a second switching element connected to the first switching element at a node;
• a transformer having a primary coil and a secondary coil, the primary coil being connected to the node;
• a low-pass filter including an output port and an input port connected to the secondary coil;
• an output terminal connected to the output port of the low-pass filter;
• a detector for outputting a voltage that follows a voltage at the output terminal;
• a reference signal generator for generating a reference voltage;
• a comparator unit for outputting a signal based on a result of comparison between the voltage supplied from the detector and the reference voltage;
• and
• an operation pause circuit operable to
• during a first period, cause the first switching element and the second switching element not to conduct regardless of the signal output from the comparator unit, and
• during a second period, cause one of the first switching element and the second switching element to conduct and a remaining one of the first switching element and the second switching element not to conduct based on a level of the signal output from the comparator unit, wherein
• the comparator unit is operable to
• output a signal of a first level when the voltage output from the detector is higher than the reference voltage, and
• output a signal of a second level when the voltage output from the detector is lower than the reference voltage, and
• the operation pause circuit is operable to
• during the second period, cause the first switching element to conduct and cause the second switching element not to conduct when the comparator unit outputs the signal of the first level, and
• during the second period, cause the first switching element not to conduct and cause the second switching element to conduct when the comparator unit outputs the signal of the second level.