Allegro Microsystems, LLC

Pablo Javier Bolsinger

Ezequiel Rubinsztain

Juan Manuel Cesaretti

Ravi Vig

Alberto Bilotti

Manuel Rivas

Apparatus includes an ADC configured to convert an analog signal to a digital signal, a comparator having a first input responsive to the analog signal, a second input responsive to the digital signal, and an output at which a comparison signal is provided, and an output checker configured to process the comparison signal to generate a fault signal indicative of whether a fault has occurred in the ADC. The comparator can be an analog comparator in which case the digital signal is converted to an analog signal for the comparison or a digital comparator in which case an additional ADC is provided to convert the analog signal into a digital signal for the comparison. Embodiments include more than one ADC in which case summation elements are provided to sum the analog signals and the digital signals for the comparison.

Diagnostic circuits and methods for analog-to-digital converters

A multichannel magnetic field sensor including a plurality of magnetic field sensing elements includes a multiplexed signal path. A front end amplifier is coupled to receive a first magnetic field signal during a first time interval and a second magnetic field signal during a second time interval. A first low pass filter processes the amplified signal during the first time interval and a second low pass filter processes the amplified signal during the second time interval. A sinc filter is coupled to receive the first low pass filtered signal during the first time interval and the second low pass filtered signal during the second time interval. A Schmitt trigger circuit includes a comparator to process the sinc filter output signal and to generate a first comparator output signal during the first time interval and a second comparator output signal is provided during the second time interval.

Multichannel magnetic field sensor with multiplexed signal path

A method for testing a signal path in a sensor, the signal path including a filter circuit and a comparator circuit, the method including: closing a first signal line that is arranged to bypass a first capacitor in the filter circuit; injecting a test signal into the signal path after the first signal line is closed; and detecting whether a signal that is output by the comparator circuit in response to the test signal satisfies a predetermined condition.

Signal path monitor

A sensor includes an output circuit configured to generate a sensor output signal based on an input signal having a logic high or low level, as may be provided by a Schmitt trigger circuit. During normal operation, the output switches between a first percentage of the supply voltage for logic high and a second percentage of the supply voltage for logic low. To convey a failure at the output, an output signal is output as either ground or the supply voltage when a fault is detected. As such, a fault can be communicated any time the output voltage is not equal to the first percentage or the second percentage of the supply voltage.

Ratiometric sensor output topology and methods

Apparatus and methods provide an output signal indicative of a failure of a filter circuit and/or a Schmitt trigger circuit of a magnetic field sensor. A magnetic field sensor includes one or more magnetic field sensing elements that generate a magnetic field signal, a filter circuit that filters the magnetic field signal, a Schmitt trigger circuit that compares the filtered signal to a Schmitt trigger threshold during a first time period, and a diagnostic circuit coupled to the filter circuit that compares the Schmitt trigger threshold to a diagnostic threshold during a second time period that does not overlap with the first time period. An output signal indicative of a failure is output when the diagnostic threshold is greater than a predetermined percentage or absolute value above or below the Schmitt trigger threshold.

Diagnostic methods and apparatus for magnetic field sensors

A sensor is provided having a magnetic field sensing element to generate a magnetic field signal, a switching circuit coupled to receive the magnetic field signal and generate a switching signal that changes a polarity of the magnetic field signal at a predetermined frequency, and a comparison device configured to receive the switching signal and generate an output signal that changes a level in response to the switching signal crossing a predetermined threshold. The switching circuit is disposed between the magnetic field sensing element and the comparison device and can provide the comparison device an input signal (i.e., the switching signal) that changes polarity at the predetermined frequency. The comparison device can sense characteristics, such as but not limited to crossing operate and release threshold levels, of both north and south polarity magnetic field signals using the switching signal.

Omnipolar schmitt trigger

An electronic comparison circuit can identify at least three conditions of an input signal received by the electronic comparison circuit. A first one of the at least three conditions occurs when a value of the input signal is less than a first threshold value, a second one of the at least three conditions occurs when a value of the input signal is greater than the first threshold value and less than a second threshold value, and a third one of the at least three conditions occurs when a value of the input signal is greater than the second threshold value. A magnetic field sensor can use the electronic comparison circuit.

Electronic comparison circuit to identify at least three conditions of an input signal

A sensor includes a Hall cell and a compensation circuit for subtracting a magnet background field from the Hall cell output to provide a signal corresponding to rotations of a toothed ferrous gear.

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Buenos Aires, Argentina

Pablo Javier Bolsinger