ABNORMALITY DETECTING DEVICE OF DEVICE FOR DRIVING ELECTRICAL LOAD AND IC FOR DRIVING ELECTRICAL LOAD

摘要

PROBLEM TO BE SOLVED: To surely detect that any of transistors for energization suffers an open failure in a device that causes current flow to one electrical load with a plurality of transistors for energization.;SOLUTION: In a device 40 for driving an electrical load L with two FETs 1 and 2 connected in parallel, the FET 1 is turned on when a control signal Sc from a microcomputer 10 is high, and the FET 2, however, is turned on when a signal Sd obtained by delaying the control signal Sc only by a prescribed period of time Td with a delay circuit 42 is high. Also, a comparator 20 outputs high if a drain voltage Vo of the FETs 1 and 2 is at a level when the FETs 1 and 2 are turned off. The microcomputer 10 decides that a FET which should be turned on when the FET is singly turned on suffers on open failure, if an output of the comparator is high both when the FET 1 is singly turned on until the prescribed period of time Td passes with the control signal Sc high and when the FET 2 is singly turned on until the prescribed period of time Td passes with the control signal Sc low.;COPYRIGHT: (C)2003,JPO