| 摘要 |
PURPOSE:To surely protect transistors, IC, etc., by comparing a reference voltage level with an abnormal voltage level of an output terminal and accelerating a normal abnormality detecting action and its resulting protecting action by means of the output signal obtained when the abnormality is detected. CONSTITUTION:A terminal #1 is connected to a power supply VCC as shown by a dotted line by some unexpected factor. In such a case, an output current Io is not regulated by a load coil RL and a large current flows to a transistor TR Q1. At the same time, the collector voltage Vo is set at the same level as the VCC. Thus, the voltage VB rises up to satisfy Vref1<VB although a voltage drop is caused by a resistance R2. As a result, a TR Q2 is turned on with a comparator 2 and an output voltage V1 of the TR Q2 is supplied to a joint between resistances R6 and R7 of a TSD circuit 3. Thus, a TR Q5 is quickly turned on in response to said accident. In such a constitution, the power TR Q1 and then in IC are protected.
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