| 摘要 |
PROBLEM TO BE SOLVED: To provide a fail safe type DC digital output circuit with which the spread of fault or the like can be prevented by diagnosing the fault of an output element by itself. SOLUTION: Mutually serially connected output elements 1 and 2 are provided between a DC power source for load drive for directly driving a load and that load, 1st and 2nd output control circuits 10 and 20 are provided for controlling the drive of the respective output elements 1 and 2, and a hit pulse generating circuit 28 is provided for instantaneously hitting the driving output of the output element 2. The output states of output elements 1 and 2 detected by 1st and 2nd monitor input circuits 16 and 26 are compared with the driving outputs of output elements 1 and 2 by 1st and 2nd comparator circuits 12 and 22 and when the both are different, the self-diagnosis of faults at the output elements 1 and 2 is performed. At the same time, the pulse output of the hit pulse generating circuit 28 is directly compared with the output state of the output element 2 by the 2nd comparator circuit 22 and when the both are different, the self- diagnosis of a short-circuiting fault at the output element 2 is performed. When the fault at any one of output elements 1 and 2 is diagnosed, the driving outputs of both the elements are turned off. |
