| 摘要 |
PURPOSE:To protect circuits during reverse connection of batteries without installing large exclusive diodes for current bypass conventionally attached on outer portion in an electronic controller installed on a car. CONSTITUTION:At the time of normal connection, a battery 11 supplies 12VDC to an electronic controller installed on a car 13 through a fuse 12. A CPU 25 of the electronic controller operates on a 5V power supply prepared by a power supply IC22 and controls drive circuits 41 and 42 by means of control signals 43 and 44 output in response to an input signal 28. Drive circuits 41 and 42 drive actuators 31 and 32 based on said control signal. When a counter- electromotive force current occurs within the circuit in response to the drive operation of the drive circuit, this current flows by bypassing a parasitic diode connected in parallel to a power MOS FET forming the drive circuits 41 and 42. On the other hand, if the battery 11 is connected reversely, the reverse current flow to these parasitic diodes, the fuse 12 is melted and the circuit is protected. |
