Allegro : Linear Hall-effect sensor provides a PWM output

The new A1354 from Allegro MicroSystems Europe is a high-precision, programmable two-wire Hall-effect linear sensor that provides a pulse width modulated (PWM) output with a duty cycle proportional to an applied magnetic field. The new device is the first linear Hall-effect sensor from Allegro to include a voltage regulator, which allows the device to be powered directly from a battery with a forward supply voltage in the range from 4.5 V to 18 V.   

The A1354 converts an analogue signal from its internal Hall sensor element to a digitally encoded PWM output signal. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analogue output signal. 

This new device 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 A1354 incorporates a monolithic BiCMOS circuit integrating a Hall element, 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.

The dynamic offset cancellation circuitry reduces the residual offset voltage of the Hall element, which is normally caused by device overmoulding, temperature dependencies, and thermal stress. The high-frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.

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.
A typical application is liquid-level sensing in automotive fuel tanks, where the number of wires going into the fuel tank is limited and the length of the wires to the control units may be long enough to introduce noise coupling.
Output duty cycle clamps provide short circuit diagnostic capabilities, while a test mode at start-up allows users to calibrate out the effects of ground potential and threshold variance at start-up in automotive engine control unit applications.

The A1354 sensor is supplied in a low-profile (1 mm thick) lead (Pb) free 4-pin single inline package (KT suffix), with 100% matt tin leadframe plating. Operating temperature range is -40°C to +125°C.

About Allegro

Allegro MicroSystems, Inc. is a leader in developing, manufacturing and marketing high-performance power integrated circuits and integrated Hall-effect magnetic sensors. Allegro’s innovative solutions serve high-growth applications within the automotive, communications, computer/office automation, consumer and industrial markets. Allegro is headquartered in Worcester, Massachusetts (USA) with design and applications centres located in North and South America, Asia, and Europe. 

Allegro MicroSystems Europe, headquartered in Chertsey, United Kingdom, is the European sales and marketing operation, and operates a network of representatives and distributors throughout Europe. Allegro also has an engineering design centre in Edinburgh in Scotland and an application and marketing centre in Annecy in France.

Allegro MicroSystems Europe Ltd
Melita House
124 Bridge Road
KT16 8LH
Tel: +33 (0) 4 50512359
Fax: +33 (0) 4 50512083

Note: The above text is the public part of the press release obtained from the manufacturer (with minor modifications). EETimes Europe cannot be held responsible for the claims and statements made by the manufacturer. The text is intended as a supplement to the new product presentations in EETimes Europe magazine.

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