REVERSE CURRENT PROTECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To apply the necessary voltage to a device power supply circuit by reducing a voltage drop in a backward current preventing circuit connected between a battery and the device power supply circuit. SOLUTION: The drain of a MOSFET 3 is connected to a terminal 1 in the positive pole side of a battery and a source thereof is connected to a terminal 2 in the device side. The gate of the MOSFET 3 is connected to the drain via a resistance component 4. In order to monitor the power supply potential of device, one input terminal a of a potential comparison circuit 5 is connected to the source of MOSFET 3 and the other input terminal b of the potential comparison circuit 5 is connected to the drain of MOSFET 3. An output terminal of the potential comparison circuit 5 is connected to the connecting point of the gate of MOSFET 3 and the resistance component 4. The potential comparison circuit 5 outputs a low level when the input terminal a side is at higher potential than that of the input terminal b side and turns into a high impedance state in the reverse case.