| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic detection apparatus which has a fast response speed to a change in magnetic flux density when the magnetic flux density is in a transition state and requires a small consumption current when the magnetic flux density is in a steady state. SOLUTION: A magnetic detection section 1 for intermittently detecting whether the magnitude of magnetic flux density B is not less than a threshold includes: a magnetic sensor 11 for detecting the ambient magnetic flux density B; and an absolute differential value calculation circuit 12 for calculating an absolute differential value Vd between an output voltage Vsns of the magnetic sensor 11 and a preset reference voltage Vref. A sample-and-hold circuit 2 samples the absolute differential value Vd intermittently outputted from the absolute differential value calculation section 12 for holding during a pause period of intermittent operation. An intermittent operation control section 3 reduces a period of an intermittent operation control signal CNT as a value Vdh of the absolute differential value held by the sample-and-hold circuit 2 is smaller, and reduces an interval of intermittent operation of the magnetic detection section 1. COPYRIGHT: (C)2011,JPO&INPIT
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