| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply that stably operates, even in a range in which the on-width of a switching element is narrowed caused by a high input voltage, or the like. SOLUTION: The switching power supply converts a direct-current voltage inputted by a switching operation of a switching element 2 into a predetermined voltage and supplies it to a load 14. The switching power supply includes a current mode control unit that carries out on/off-control on the switching element 2, based on the result of comparison between an error amplification signal corresponding to the difference between the value of output voltage supplied to the load 14 and a predetermined reference voltage and a current detection signal corresponding to the value of current which passes through the switching element 2; a voltage-mode control circuit 16 that carries out on/off-control on the switching element 2, based on the result of comparison between the error amplification signal and a ramp signal with a predetermined frequency; and a control-mode selecting unit that selects either the current-mode control unit or the voltage-mode control circuit 16 to on/off-control the switching element 2. COPYRIGHT: (C)2011,JPO&INPIT |
