| 摘要 |
PROBLEM TO BE SOLVED: To provide a load drive circuit in which an overcurrent protective current value is designed easily and which can prevent an element breakdown due to an overcurrent. SOLUTION: A power supply 1, a load 2 and a power transistor T1 are connected in series, and a series circuit of a transistor T3 for current detection and a resistor 9 for current detection is connected in parallel to the power transistor T1. A control circuit 3 switching-controls both transistors T1, T3. The base terminal of a protective transistor T4 is connected across the transistor T3 and the resistor 9, when a voltage generated across both terminals of the resistor 9 exceeds a prescribed value, a voltage across control terminals of the transistors T1, T3 is adjusted forcibly, and a current flowing to the load 2 is limited. A negative characteristic as a temperature characteristic of the resistor 9 is provided with reference to the protective transistor T4 having a negative temperature characteristic. COPYRIGHT: (C)2003,JPO
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