The new A1354 from UK-based Allegro MicroSystems Europe is a programmable, precision two-wire Hall-effect linear sensor that has a pulse-width modulated (PWM) output with duty cycle proportional to the applied magnetic field. It incorporates a voltage regulator, which allows the device to be powered directly from a battery with a supply voltage of 4.5 V to 18 V. The A1354 converts the analogue signal from its internal Hall sensor element to a digitally encoded PWM output signal.
The A1354 is targeted at position sensing applications in the automotive and industrial sectors, particularly where diagnostic capabilities are required, where there is a limitation on the number of wires to and from a control unit, or where noise immunity over long wires is required. The noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analogue output signal.
The A1354 incorporates precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. Dynamic offset cancellation reduces the residual offset voltage of the Hall element. High-frequency offset cancellation enables a higher sampling rate, which increases the accuracy of the output signal and enables faster signal processing.
Programmable features include sensitivity, PWM frequency (15 Hz or 120 Hz) and unidirectional or bidirectional sensing. Programmability allows the device to be fine-tuned in the final application for higher system accuracy. Output duty cycle clamps provide short-circuit diagnostic capability, while a start-up test mode allows users to calibrate out the effects of ground potential and threshold variance in use.
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