Patent ID: 9720052
Date: 2017-08-01
CPC Classifications: G01R

Claim:
1. A magnetic sensor drive circuit that measures a magnetic field by passing a feedback current, which cancels a change in magnetic flux density using the measured magnetic field, through a predetermined coil, the drive circuit comprising: a first circuit block which controls the feedback current which is passed through the predetermined coil, has a feedback current control circuit which outputs a signal according to the strength of the feedback current which is passed through the predetermined coil, and passes the feedback current which is passed through the predetermined coil using an external power source, which is input from an external power source input terminal, as the power source; a second circuit block which has a ratiometric control circuit that monitors a voltage of the power source and an output adjustment circuit which adjusts a value of the output signal of the feedback control circuit to a value which is proportional to the power source voltage based on an output signal of the ratiometric control circuit and outputs the value as a sensor output signal; a first power source line which supplies the external power source to the first circuit block; a second power source line which supplies the external power source to the second circuit block in parallel to the first power source line; a first low-pass filter inserted into the first power source line; and a second low-pass filter inserted into the second power source line.