Allegro Microsystems, LLC

Virag V Chaware

Aaron Cook

Craig S Petrie

Jesse Lapomardo

David Jamie Haas

Michael G Ward

Kenneth Snowdon

Stephen Marshall

Vladimir Kravljaca

John Waranowski

Method and apparatus for trimming a magnetic field sensor having a first magnetic field sensing element. The trimming includes the use of a curve for normalized sensitivity of the first magnetic field sensing element derived from a first curve corresponding to current through a coil in a first direction at a first time. This produces a field affecting the first magnetic field sensing element versus an external field. The trimming further includes a second curve corresponding to current through the coil in a second direction opposite to the first direction at a second time to produce a field affecting the first magnetic field sensing element versus an external field.

Methods and apparatus for trimming a magnetic field sensor

Described embodiments provide a magnetic field sensor that includes first and second spaced magnetic field sensing elements that each generate a signal indicative of a magnetic field associated with a target. A switching module couples a first terminal of the first magnetic field sensing element having a first polarity to a first terminal of the second magnetic field sensing element having a polarity opposite the first polarity to generate a first combined signal. The switching module couples a second terminal of the first magnetic field sensing element having a polarity opposite the first polarity to a second terminal of the second magnetic field sensing element having the first polarity to generate a second combined signal. The switching module simultaneously couples the first and the second combined signals to an amplifier, which generates an output signal indicative of the magnetic field that has stray magnetic field effects cancelled.

Magnetic field sensors having stray field rejection

Apparatus including a regulator configured to generate a regulated output and a diagnostic circuit configured to generate a diagnostic signal indicative of whether the regulator is able to maintain regulation is described. The regulator includes an amplifier having a first input responsive to a reference voltage, a second input responsive to a feedback signal associated with the regulated output, and an output at which a control voltage is provided and further includes a pass element controlled by the control voltage and coupled to a node which the regulated output is provided. The diagnostic circuit is responsive to the control voltage and to the reference voltage to generate the diagnostic signal. The regulator may be a voltage regulator or a current regulator and in some embodiments, the diagnostic signal takes the form of a composite signal indicative of whether a voltage regulator and whether a current regulator can maintain regulation.

Circuits and methods for regulator diagnostics

A sensor integrated circuit includes a disturb immune memory configured to store data and a digital processor coupled to the disturb immune memory and including a main register. The digital processor is configured to perform one of a fast reset or slow reset of the main register according to a level of a supply voltage to the integrated circuit. The fast reset includes resetting the main register according to the data stored in the disturb immune memory and the slow reset includes resetting the main register according to a default state.

Supply voltage disturbance immunity for digital circuits

An apparatus comprises a first measurement circuit having a first magnetic field sensing element to detect a measured magnetic field and produce a first signal representing the measured magnetic field, and a first signal processing circuit to process the first signal to produce a first processed signal. A second measurement circuit comprises a second magnetic field sensing element to detect a measured magnetic field and produce a second signal representing the measured magnetic field, and a second signal processing circuit to process the second signal to produce a second processed signal. A diagnostic processing circuit is coupled to receive the first signal and the second signal and configured to process the first signal during a first time period to produce a first diagnostic signal, and process the second signal during a second time period. A logic circuit determines if an error is present.

Efficient signal path diagnostics for safety devices

A magnetic field sensor comprises at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field; a diagnostic circuit configured to generate a diagnostic signal, wherein the diagnostic signal is not dependent on a measured magnetic field; a signal path comprising an amplifier and an analog-to-digital converter for processing the measured magnetic field signal to generate a sensor output signal indicative of the external magnetic field during a measured time period and for processing the diagnostic signal during a diagnostic time period; and a switch coupled to receive the measured magnetic field signal and the diagnostic signal and direct the measured magnetic field signal to the signal path during the measured time period and direct the diagnostic signal to the signal path during the diagnostic time period.

Magnetic field sensor with shared path amplifier and analog-to-digital-converter

An electronic amplifier has a feedback circuit with a transconductance amplifier.

Electronic amplifier with a feedback circuit that includes a transconductance amplifier

In one aspect, a current driver, includes an operational amplifier that includes a first input port configured to receive a reference signal and a second input port configured to receive a variable signal. The variable signal is a function of an output current of the current driver. The reference signal corresponds to a selected maximum output current of the current driver. The current driver also includes a feedback transistor comprising a gate coupled to the output of the operational amplifier and a summing junction coupled to a drain of the feedback transistor and configured to receive a signal from the drain to enable clamping of the output current of the current driver to the maximum output current when the variable signal exceeds the reference signal. The summing junction is coupled to a set of transistors configured to provide the output current of the current driver.

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Nashua, NH, United States of America

Virag V Chaware