Spannungsregler für ein Kraftfahrzeug

摘要

The present inventions provides a generated-voltage regulator for an automobile, in which the on state of a key switch can be detected securely without being affected by a change in ambient temperature or the like. According to a selected embodiment, when a generation failure occurs in a power generation circuit 12, a power MOS FET 111 is turned on and off periodically so that a charge lamp 3 is lighted. The on/off state of the MOS FET 111 is detected by a detecting section 1121 of a voltage detecting circuit 112. Being supplied with an on signal from the detecting section 1121, a holding section 1122 turns the level of its output signal c to an "H" level only for a predetermined period. As a result, the key switch 2 is not judged to be off even in the case where the MOS FET 111 is turned on, and the on state of a switch 116 is maintained. Accordingly, the power MOS FET 111 which is low in the level of the drain-source voltage thereof in an on state but is small in size, light in weight and small in a heat value, can be employed as a switching section for lighting the charge lamp. Consequently, there is provided a generated voltage regulator in which not only the on state of the key switch can be detected securely regardless of the change of ambient temperature or the like but reduction both in size and in weight can be attained.