| 摘要 |
PROBLEM TO BE SOLVED: To simplify the constitution of a current detecting circuit, and to attain high precision. SOLUTION: A load current detecting circuit 20 for detecting currents running through a coil 21 of a linear solenoid has only one resistance for detecting currents connected between the coil 21 and a low side switch 23. When a high side switch 22 and the low side switch 23 are turned into an ON state, control currents I1 are allowed to run from a DC power source +B to GND. When either the high side switch 22 or the low side switch 23 is turned OFF, induced currents I2 are allowed to run from the coil 21 through a resistance 25 and a diode 24. Those currents are detected by the resistance 25, and amplified by an amplifier circuit 26 for detecting currents so that an output corresponding to the currents can be derived. The amplifier circuit 26 for detecting currents has a differential amplifier circuit having a dead band at a high level side and a differential amplifier circuit having a dead band at a low level side which are switched so as to be used according to an input voltage so that high precision can be attained.
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