Date: 12/02/2009

Temperature-stable and stress-resistant Hall-effect switches and latches

Allegro Microsystems has released new family of Hall-effect sensor based switches and latches that can withstand extreme temperatures and stresses suited for operation over extended temperature ranges to 150°C. High temperature performance is achieved through dynamic offset cancellation, reducing the residual offset voltage normally caused by device over-molding, temperature dependencies, and thermal stress. Allegro's A1220 and A1221 sensor devices are most commonly used to detect the speed and direction of ring magnets for motor commutation. The A1120 is most commonly used to detect the end position in wiper systems and multiple discrete positions in shift selectors.

Each device includes on a single silicon chip: a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and short-circuit protected open-collector output that can sink up to 25 mA. An on-board regulator permits operation with supply voltages of 3.0 to 24 V. Significant advantages are realized by reducing the minimum operating voltage. These devices can now be used in 3 V applications and additional external resistance can be added in series with the supply pin for greater protection against transient events. Two package styles provide a magnetically optimized package for most applications. Package type LH is a modified SOT23W, surface mount package, while the UA is a three-lead, ultra-mini-SIP for through-hole mounting. Each package type is available as lead (Pb) free (suffix, -T), with a 100% matte tin-plated lead frame.