Allegro MicroSystems Inc.'s A1356 is a high precision, user programmable, Hall-effect linear
sensor with a pulse width modulated (PWM), open collector output. The duty
cycle (DC) of the PWM output signal (freq: 2†kHz) is proportional to an
applied magnetic field. The A1356 device converts an analog signal from its
internal Hall sensor element to a digitally encoded PWM output signal.
The BiCMOS, monolithic circuit inside of the A1356
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 over molding, 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 design and manufacturing flexibility of the A1356
is realized through user programmable: gain, quiescent duty cycle and carrier
frequency. The device can be set up in a magnetic circuit and programmed with a
train of serial pulses. Once the appropriate parameters have been selected, the
codes can be locked for one-time programming. In this manner, manufacturing
tolerances 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 frame
plating. It is priced at $1.45 in quantities of 1,000.