Patent ID: 7956598
Filing Date: 2011-06-07
Classification: H03K

Abstract:
1. A variable voltage dividing circuit, comprising: a voltage dividing unit which includes a resistor string formed of a plurality of resistors connected in series and outputs divided voltages divided at connection points of the plurality of resistors, one end of the resistor string being applied with a first voltage, another end thereof being applied with a second voltage, wherein the voltage dividing unit outputs a plurality of threshold voltages that represent detection magnetic flux density and release magnetic flux density of a magnetic sensor, the threshold voltages comprising a first detection voltage, a first release voltage, a reference voltage, a second detection voltage and a second release voltage with a relationship of the first detection voltage>the first release voltage>the reference voltage>the second release voltage>the second detection voltage; a first constant current source connected to a first connection point of the resistor string; and a second constant current source connected to a second connection point located symmetrically to the first connection point with respect to a center of the resistor string in the resistor string, wherein, in accordance with a voltage difference between the first voltage and the second voltage, one of the first constant current source and the second constant current source subtracts a first adjustment current from a current flowing through the resistor string, and another thereof feeds a second adjustment current to the resistor string; wherein in response to a change in the voltage difference between the first voltage and the second voltage, the first constant current source and the second constant current source adjust the first adjustment current and the second adjustment current such that hysteresis widths of a difference between the first detection voltage and the first release voltage and a difference between the second detection voltage and the second release voltage are kept as a constant potential difference.