Hall Effect Latch for High Temperature Operation A1225, A1227, and A1229

Features and Benefits

• Symmetrical switchpoints
• Superior temperature stability
• Operation from unregulated supply
• Open-drain 25 mA output
• Reverse Battery protection
• Activate with small, commercially available permanent magnets
• Solid-state reliability
• Small size
• Resistant to physical stress
• Enhanced ESD structures result in 8 kV HBM ESD performance without external protection components
• Internal protection circuits enable 40 V load dump compliance without external protection components

Description

These Hall-effect latches are extremely temperature-stable and stress resistant sensor ICs especially suited for operation over extended temperature ranges to 150¡ãC. Superior hightemperature 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 ¨C40¡ãC to 150¡ãC. 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.

Functional Block Diagram