| 摘要 |
PURPOSE:To prevent the failed operation of a device, by detecting a power supply voltage for control section that it does not reach a normal voltage and interrupting a driving power supply, in a device using the controlling power supply and the power supply for driving section controlled with the control section. CONSTITUTION:In a power supply 3 for a driving circuit 4 controlled with a control section circuit 2 and a controlling section power supply 1, a protective circuit consisting of transistors (TR) Q1, Q2, Q3, Zener diode DZ, and resistors R1, R2, R3 is added between lines which tie the power supply 1, circuit 2, power supply 3 and line 4. If a voltage of the power supply 1 does not reach a normal voltage, this is detected at the diode DZ, and a current flowing from the power supply 1 to the circuit 4 is cut off via the TRs, allowing to prevent abnormal operation of the circuit 4. |
