METHOD AND DEVICE FOR DETECTING FAILURE WITHIN RANGE OF STATE RESPONDING SENSOR

摘要

PROBLEM TO BE SOLVED: To provide a method and a circuit for simply and cost-effectively detecting the occurrence of a failure within a range in an output of a Wheatstone bridge. SOLUTION: A first circuit part 13 generates a common mode voltage VCM from a bridge output of a Wheatstone bridge element 12 made up of piezoresistance elements R1 to R4, and second the third circuit parts 14, 15 generate a centering voltage C*VBRG equal to the common mode voltage for sensor calibration and a window voltage W*VBRG from a bridge voltage VBRG. An effective range C*VBRG-W*VBRG to C*VBRG+W*VBRG of the bridge output is set by a pair of address SUM 1, 2, and compared with the common mode voltage VCM by comparators Q1 to Q3. If it is detected to be out of the effective range, an alarm is issued.