Hall-Effect Position Sensors Come In Miniature Packages

Enlarging its portfolio of position-detecting sensors, Allegro MicroSystems Inc. has introduced a family of programmable, Hall-effect, linear sensors in miniature package options (see the Figure). The A138x family comes in either a TO-92 three-lead, single in-line package or an SOT-23W three-lead, surface-mount package, offering the accuracy and flexibility of fully programmable linear sensors without the penalty of a larger package and higher cost. The analog devices incorporate one-time-programmable (OTP) ROM to allow users to optimize the device in a finished sensor assembly. This optimization reduces inaccuracies caused by manufacturing tolerances and simplifies the assembly process. Also, the patented dynamic offset cancellation provides extremely low offset and minimal temperature drift.

A series of voltage pulses on the output of either three-lead package permits users to finely adjust the device's sensitivity around one of four predetermined nominal values (2.5 mV/G, 3.1 mV/G, 5.0 mV/G, and 7.0 mV/G). Greater flexibility is available by means of adjusting the quiescent output voltage (the output without the presence of a magnetic field) and the temperature coefficient, as well as by setting the output polarity for each device. The family's temperature coefficient is designed to compensate for temperature coefficients of typical samarium cobalt (SmCo) magnets.