| 摘要 |
PURPOSE:To prevent failure of a voltage converter by stopping the operation of each voltage converter by an input voltage monitor if an input voltage becomes abnormal. CONSTITUTION:An input voltage from a main power source is monitored by an input voltage monitor 2, and if it falls within a normal voltage, Q2 of the monitor 2 is operated, a control voltage is applied to voltage converters 3-5, and a voltage converter is operated. If the input voltage becomes higher than a normal voltage, a high voltage monitoring Zener diode D0 is in continuity Q0 is turned ON, and thereby Q1, Q2 are turned OFF. If the input voltage is lowered, a low voltage monitoring Zener diode D1 is interrupted, and thereby the Q2 is turned OFF. When the Q2 is turned OFF, a reference voltage generator is not operated, and hence the operation of the converter is stopped. |
