| 摘要 |
PROBLEM TO BE SOLVED: To limit a voltage precisely by a small number of elements. SOLUTION: A 1st transistor(TR) Q1 and a 2nd TR Q2 of diode-connection constitution constitute a differential pair and the 1st and 2nd TR Q1 and Q2 are set nearly equal in emitter current density to each other. When the base- collector voltage of the 2nd TR Q2 connected to the output terminal of a controlled circuit 2, i.e., the output voltage of the controlled circuit 2 becomes higher than the limit voltage VLim applied to the base of the 1st TR Q1, the 2nd TR Q2 operates and the output voltage is fixed to the limit voltage VLim. Further, the emitter current of the 1st TR Q1 is set smaller than the emitter current of the 2nd TR Q2 and then the current consumption is made small without lowering the limit precision of the voltage limiter circuit 1.
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