| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable the shutdown stably without damaging a constant current source transistor of a constant current circuit. <P>SOLUTION: A current changeover circuit has an emitter-follower circuit (an EF circuit), a constant current circuit, and a switch SW1 that turns on and off the constant current circuit. The EF circuit consists of a transistor Q1 having a base connected to a signal input terminal IN1, a collector connected to a power source VCC1, and an emitter connected to a signal output terminal OUT1. The constant current circuit consists of: a transistor Q2 having a base connected to an output of the switch SW1 and a collector connected to the emitter of the transistor Q1; a resistance RS1 having a first terminal connected to the emitter of the transistor Q2 and a second terminal connected to a power source VEE1; and a leakage current source JREAK1 having a first terminal connected to the collector of the transistor Q2 and a second terminal connected to the power source VEE1. <P>COPYRIGHT: (C)2012,JPO&INPIT |
