| 摘要 |
PURPOSE:To protect a DC power supply against its adverse connection, to prevent the deterioration in performance of a main circuit and a protecting circuit, and also to suppress the voltage drop and the power consumption of the protecting circuit. CONSTITUTION:A protecting circuit 3 is provided with a switch element Q1 which is inserted between a DC power supply E and a main circuit 1 so that a parasitic diode D1 which consists of an enhancement type MOSFET and set between the drain and the source is set in the forward direction. When the power supply E has the adverse polarity, the element Q1 is turned off by the output of a comparator CP1 based on the both-terminal potential of the element Q1. Under such conditions, the diode D1 of the element Q1 is set in reverse to the power supply E which is reversely connected. Therefore the currents passing through the element Q1 and the circuit 1 can be surely prevented. |
