Date: 22/04/2010

Hall-Effect latches withstanding extreme environment

Allegro's new line of Hall-effect latches A1225, A1227 and A1229 devices withstands extreme temperature up to 150 Deg C. These latches are suitable for applications requiring high voltage transient protection close to the sensors inside the system. By offering ESD protection up to 8 kV HBM without external protection components and internal protection circuits, these device survive 40 V load dump compliance without external protection components. The right example applications for these new devices are motor commutation applications in sunroofs and power windows within the automotive market.

The high temperature performance is achieved by using 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.

To know more visit www.allegromicro.com