Integrated Hall-effect sensors shrink position sensors and motor drivers
By Margery Conner, Technical Editor -- EDN, July 12, 2007
Fine-pitch-detection applications incorporating encoder ring-magnets require precise alignment of their location sensors. With that requirement in mind, Allegro Microsystems recently introduced the A3423 dual-channel direction-detection sensor. The device has two Hall-effect elements that are photolithographically aligned to more than 1 micron to ensure sensitivity and temperature stability in harsh automotive and industrial environments. The device offers short-circuit-protected speed and direction outputs, and its input operating voltage ranges from 3.8 to 24V. The A3423 is available in a four-pin SIP and a plastic, eight-pin SOIC surface-mount package; a SOIC version is in development.It sells for $1.78 (1000); leadtime is 14 weeks.
The company also introduced the A1442 full-bridge motor driver for low-voltage, bipolar, brushless-dc motors, which often find use as vibration motors in cellular phones, pagers, electronic toothbrushes, handheld-video-game controllers, and low-power fans.The 1442’s Hall-effect sensor provides motor commutationby detectingthe rotational position of an alternating-pole ring magnet. The device comes with the Hall-element sensor, the motor-control circuitry, and the full-output bridge. The input voltage goes as low as 1.8V and includesreverse-battery and output-short-circuit protection. The six-pin MLP/DFN package measures 1.5×2×0.4 mm and sells for 39 cents (1000); leadtime is six to eight weeks.
