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Allegro MicroSystems, Inc. Introduces Hall-Effect Latches with Increased Protection for High Voltage Transients

April 20, 2010
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Worcester, MA – Allegro MicroSystems, Inc. adds several new devices to their existing line of Hall-effect latches. The A1225/A1227 and A1229 devices are extremely temperature-stable and stress resistant sensor ICs especially suited for operation over extended temperature ranges to 150°C. The intent of these latches is to provide a more robust product offering for those applications that require high voltage transient protection close to the sensors inside the system. Enhanced ESD structures provide ESD protection up to 8 kV HBM without external protection components and internal protection circuits enable these device to survive 40 V load dump compliance without external protection components. These new devices are targeted at motor commutation applications in sunroofs and power windows within the automotive market.

Superior high temperature performance is made possible through a novel Schmitt trigger circuit that maintains operate and release point symmetry by compensating for temperature changes in the Hall element. Additionally, internal compensation provides magnetic switchpoints that become more sensitive with temperature, hence offsetting the usual degradation of the magnetic field with temperature. The symmetry capability makes these devices ideal for use in pulse-counting applications where duty cycle is an important parameter.

The three basic devices (A1225, A1227, and A1229) are identical except for magnetic switchpoints. Each device includes on a single silicon chip a voltage regulator, Hall-voltage generator, temperature compensation circuit, signal amplifier, Schmitt trigger, and a buffered open-drain output to sink up to 25 mA. The on-board regulator permits operation with supply voltages of 3.8 to 24 V.

The first character of the part number suffix determines the device operating temperature range. Suffix L is for –40°C to 150°C. Two package styles provide a magnetically optimized package for most applications. Suffix LT is a miniature SOT89/ TO-243AA transistor package for surface-mount applications, suffix UA is a three-lead ultra-mini-SIP. Both packages are lead (Pb) free with 100% matte tin leadframe plating.