| 摘要 |
PURPOSE:To prevent power transistors from simultaneously becoming ON by forming an interlock circuit with photocouplers. CONSTITUTION:A comparator 14 compares a signal, from which a control signal and a triangular wave are subtracted, with a reference signal 0V and outputs a signal Valpha and a signal Vbeta which is inverted by an inverter 15. When the signal Valpha is inputted to the previous stage circuit 16 of a drive circuit 9, a transistor 18 becomes ON state, and a power transistor 5 becomes ON. At this time, a voltage is applied to the light emitting unit 22a of the photocoupler, a transistor 21 becomes ON by the output of a light receiving unit 22b of the photocoupler, thereby interrupting the base input of a power transistor 6. When the signal Vbeta is inputted to the previous stage circuit 17 of a drive circuit 10, the transistor 6 becomes ON, and the base input of the transistor 5 is interrupted by the photocoupler 23(23a, 23b). |
