| 摘要 |
PROBLEM TO BE SOLVED: To obtain a power supply apparatus which is constituted at low costs and which prevents a short-circuit current from flowing into a first switching element and a second switching element. SOLUTION: A first switching element Q1 and a second switching element Q2 are used both in an inverter circuit 2 and a step-down chopper circuit 3. A regenerative current is detected by a first detecting circuit 12, using an electromotive force which is generated in a winding 16 for detection. The logical sum of the output of the first detection circuit 12 and the output of a first oscillation circuit 11 is found in a second detection circuit 13. A second oscillation circuit 14 outputs a square-wave pulse signal by making use of the output of the second detection circuit 13 as a trigger signal. Then, when the regenerative current flows, the output of the first detection circuit 12 is fixed at H-level, and no pulse signal is output from the second oscillation circuit 14. Thereby, while the regenerative current is flowing, an on-signal is not given to second switching element Q2, and a short-circuit current is prevented from flowing to the first and second switching elements Q1, Q2. |
