User-Programmable Linear Hall-Effect Sensor IC

Allegro MicroSystems Inc.'s A1356 is a high precision, user programmable, Hall-effect linearsensor with a pulse width modulated (PWM), open collector output. The dutycycle (DC) of the PWM output signal (freq: 2 kHz) is proportional to anapplied magnetic field. The A1356 device converts an analog signal from itsinternal Hall sensor element to a digitally encoded PWM output signal. The BiCMOS, monolithic circuit inside of the A1356integrates a Hall element, precision temperature-compensating circuitry toreduce the intrinsic sensitivity and offset drift of the Hall element, asmall-signal high-gain amplifier, proprietary dynamic offset cancellationcircuits and PWM conversion circuitry. The dynamic offset cancellation circuitsreduce the residual offset voltage of the Hall element, which is normallycaused by device over molding, temperature dependencies and thermal stress. Thehigh-frequency offset cancellation (chopping) clock allows for a greatersampling rate, which increases the accuracy of the output signal and results infaster signal processing capability.

The design and manufacturing flexibility of the A1356is realized through user programmable: gain, quiescent duty cycle and carrierfrequency. The device can be set up in a magnetic circuit and programmed with atrain of serial pulses. Once the appropriate parameters have been selected, thecodes can be locked for one-time programming. In this manner, manufacturingtolerances can be reduced and the assembly process can be simplified.

The A1356 sensor is provided in a lead (Pb) free,3-pin, single inline package (KB suffix), with 100 percent matte tin lead frameplating. It is priced at $1.45 in quantities of 1,000.

User-Programmable Linear Hall-Effect Sensor IC