PROTECTION CIRCUIT ON REVERSE CONNECTION OF POWER SUPPLY

• Main Authors: YUKAWA HOSHO, MAEDA SHINICHI, SHIRAKI KATSUYOSHI
• Format: Patent
• Language: English
• Published: 29.03.2007
• Subjects: CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER; CONTROLLING; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION; PHYSICS; REGULATING; SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES; SYSTEMS FOR STORING ELECTRIC ENERGY

PROBLEM TO BE SOLVED: To provide a protection circuit that is the most suitable for protection of electronic control unit (ECU) during reverse connection of a power supply. SOLUTION: In ECU45 operating on a power supply of a battery 3, n-channel FET21 is provided on a power supply wiring 15 that establishes a connection between a power supply terminal 5 connected to a plus terminal of the battery 3 and a control circuit 13 for power supply, in such a manner that an anode of its parasitic diode D1 is situated at the side of a power terminal 5. Further, n-channel FET22 is provided at a downstream side of the FET21, in such a manner that a cathode of its parasitic diode D2 is situated at FET21 side. When an ignition key switch 9 is turned on during normal connection of the battery 3, FET's21, 22 are turned on by charge pump circuits 43, 47 to which operating electricity is supplied from a drain side of FET21, and electricity of a battery 3 is supplied to the control circuit 13. Further, FET's21, 22 are turned off during reverse connection of the battery 3, and thus reverse current is inhibited by the parasitic diode D1. COPYRIGHT: (C)2007,JPO&INPIT