| 摘要 |
PURPOSE:To detect abnormal output enough without using an abnormal voltage detection circuit and a photocoupler by providing the output of an error amplifier with a means, which monitors the abnormality of the output voltage of a voltage converting circuit and outputs an alarm signal. CONSTITUTION:When a voltage converting circuit 1 is operating normally, if one or more hitches occur in the first reference voltage 2, an error amplifier 3, a triangular wave generator 4, and the first comparator 5, the output of the error amplifier 3 deviates upward or downward form the triangular level of the triangular wave generator 4. At this time, since the second reference voltage 6 is set on the level above or below the triangular wave in advance, the second comparator 7 detects the abnormality of the output level of the error amplifier 3 by comparison, and sends out an alarm signal. Hereby, the detection circuit, which was used in the past for detecting the abnormality of the output voltage, and the display circuit such as a photocoupler, etc., which displays the abnormality through an earth system, can be deleted, and abnormal output voltage can surely be detected. |
