Patent ID: 7994765

Claim:
A power supply device, comprising: a first lead terminal and a second lead terminal for connection with a load; a fuel cell; an energy storage element connected between the first and second lead terminals; a synchronous-rectification switching power-source portion for converting an output voltage of the fuel cell to an output voltage of the energy storage element and output it to the first and second lead terminals; and a current-detecting portion for detecting an output current of the fuel cell, wherein the switching power-source portion includes: a coil; a first switching element connected between the energy storage element and the coil in series; a second switching element connected to the series circuit of the first switching element and the energy storage element in parallel; and a controller for: turning the first and second switching elements on and off alternately when an output current detected by the current-detecting portion is larger than a preset current threshold, and executing a simultaneous-turn-off control of turning off the first and second switching elements simultaneously when the output current detected by the current-detecting portion is not larger than a preset current threshold.