Patent ID: 8729890

Claim:
A magnetic field sensor for sensing a rotation of an object, comprising: a semiconductor substrate having first and second parallel major surfaces; a plurality of magnetic field sensing elements disposed upon the semiconductor substrate, wherein the plurality of magnetic field sensing elements is configured to generate a respective plurality of magnetic field sensing element output signals responsive to a magnetic field having a direction component in an x-y plane parallel to the first major surface of the semiconductor substrate, the x-y plane having an x-direction and a y-direction orthogonal to the x-direction; an x-y direction component circuit disposed upon the semiconductor substrate, coupled to receive a first intermediate signal representative of the plurality of magnetic field sensing element output signals, and configured to generate an x-y angle signal as a first output signal from the magnetic field sensor indicative of an angle of the direction component of the magnetic field in the x-y plane; a rotation speed sensing circuit disposed upon the semiconductor substrate, coupled to receive a signal representative of the x-y angle signal, and configured to generate a rotation speed signal as a second output signal from the magnetic field sensor indicative of a rotation speed of the object; and a power controller disposed upon the semiconductor substrate, coupled to receive the rotation speed signal, coupled to receive a velocity threshold value, configured to compare the rotation speed signal with the velocity threshold value, and configured to generate a velocity threshold mode control signal having first and second states in accordance with the comparing, wherein a continuous mode of operation is performed when the velocity threshold mode control signal is in the first state, and wherein a discontinuous mode of operation is performed when the velocity threshold mode control signal is in the second state, wherein, during the discontinuous mode of operation, a substantial portion of the magnetic field sensor periodically powers on and off, and wherein, when in the continuous mode of operation, the magnetic field sensor continually powers on.