| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC-DC converter in which a main capacitor is not degraded due to its overcharge when a short circuit accident or the like is generated in a switching element. SOLUTION: A DC-DC converter circuit is provided with an oscillating transformer 20, with a power supply 1 and with a PNP oscillating transformer 2 used to boost a power-supply voltage. The DC-DC converter circuit is provided with an FET 5 as a first element which is connected in series with the base of the PNP oscillating transistor so as to be controlled and with an NPN transistor 17 as a second element which is connected to a feedback winding, by which a control terminal and a control terminal at the FET 5 as the first element are connected via a diode 6, which is set to continuity together with the FET 5 as the first element so as to be charged when a charging control signal S1 given to their connection part is at an H-level and which stops an oscillation at a low level. Then, even when the FET 4 cannot be controlled due to a short circuit accident, the NPN transistor 17 is turned off so as to surely stops the oscillation. |
