Wednesday, 11 January 2012

Hall-effect sensor IC

Customer-programmable linear Hall-effect sensor IC with pulse-width-modulated two-wire output

The new A1357 from Allegro MicroSystems is a high-precision, customer-programmable, linear Hall-effect sensor IC with a pulse-width-modulated current-sourced two-wire output.

Featuring a wide ambient temperature range of -40°C to +150°C, the A1357 device is targeted at the automotive and industrial sectors, particularly in applications where signals have to travel over relatively long distances in noisy environments.

The A1357 converts an analogue signal from its internal Hall sensor element to a digitally encoded PWM output signal with a frequency of 1 kHz and a duty cycle that is proportional to an applied magnetic field. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analogue output signal.

The monolithic BiCMOS circuit in the A1357 integrates 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 circuits reduce 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.

The A1357 sensor IC is supplied in a lead (Pb) free 3-pin single inline package (KB suffix), with 100% matt tin lead-frame plating.

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