Patent ID: 8008908

Claim:
A magnetic field sensor, comprising: a semiconductor substrate on which are provided two, spaced magnetic field sensing elements, each providing a magnetic field signal proportional to a sensed magnetic field associated with a magnetic article; a circuit configured to process each of the magnetic field signals only during sample intervals occurring at a sample rate and to generate a first sensor output signal indicative of a speed of rotation of the magnetic article and a second sensor output signal indicative of a direction of rotation of the magnetic article; and a clock circuit providing a clock signal to the circuit, wherein the sample rate is controlled by the clock signal and is one of a first predetermined sample rate or a second, faster predetermined sample rate, wherein the clock circuit is responsive to the first sensor output signal and is configured initially to provide the clock signal corresponding to the first predetermined sample rate and to provide the clock signal corresponding to the second predetermined sample rate in response to a change of state of the first sensor output signal.