| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC-DC converter which can realize protection for low output voltage, reduction in size and cost without use of large size element which requires higher cost. SOLUTION: In this DC-DC converter, when a sub power source voltage drops proportional to an output voltage of a secondary circuit because of short- circuit of a load 13, a fist FET 5 of the power source selection unit 41 turns on and a current flows into a resistor 6, thereby turning on a PNP transistor 25 of a latch stopping unit 50 to turn on a third FET, setting the operation control terminal of a PWM control IC 4 to the L-level to stop the conversion to AC, and stopping transfer of power source to the secondary circuit by the latching.
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