| 摘要 |
PROBLEM TO BE SOLVED: To prevent malfunctioning caused by noise, and to reduce power consumption by turning a main transistor off by a first transistor, when a voltage drop of a load current detecting resistor is not lower than a constant value.a SOLUTION: If a voltage drop in a load current detecting resistor RS exceeds a predetermined overcurrent detection voltage, a first transistor Q1 is turned on. A bias is applied at this time by currents flowing in a first resistor R1 and a second resistor R2, and a second transistor Q2 is turned on. A bias is applied at this time by currents flowing in a fourth resistor R4 and a fifth resistor R5, and a third transistor Q3 is turned on. A main transistor QM is turned off, and supply of a load current is stopped. An overcurrent is not detected after the supply stop of the load current, and feedback is applied to the control end of the second transistor Q2 through a sixth resistor R6 and a first diode D1. Consequently, overcurrent protection is performed continuously, and power consumption is reduced.
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