Melexis First to Develop 2-Wire, 2-Bit Hall Switch for Auto Sensing

Melexis recently introduced the MLX92344, a programmable Hall-effect switch designed to replace multiple mechanical microswitches in automotive position-sensing applications. The device uses a two-wire configuration while supporting up to four distinct position states. This simplifies wiring and reduces component count in systems such as seat tracks, electronic latches, charge ports, and steering column mechanisms.

The MLX92344 Hall-effect switch can detect up to four position states over a standard two-wire interface. 

What makes the MLX92344 notable is Melexis' claim that it is the world's first two-wire, two-bit Hall switch. Instead of using multiple switches to identify intermediate mechanical positions, the device can report up to four programmable states through a single contactless sensor while remaining compatible with existing automotive ECUs and wiring architectures.

Four-Position Detection Through a Single Two-Wire Interface

Automotive systems such as seat-track monitors, electronic latches, charge-port mechanisms, and steering column controls often need to identify more than just open and closed positions. Detecting intermediate positions typically requires multiple microswitches, which adds wiring, components, and installation complexity.

The MLX92344 in action.

The MLX92344 uses a two-threshold Hall sensor that reports up to four position states through a standard two-wire connection. Engineers can program different current outputs for each state, with configurable levels from 3 mA to 28 mA. This allows the device to emulate traditional microswitch interfaces while remaining compatible with existing ECUs, requiring little more than software adjustments to interpret the additional position information.

Programmability Extends Beyond Output States

The MLX92344's flexibility comes from its programmable layout, which uses on-chip non-volatile memory; engineers can adjust magnetic thresholds, output current levels, diagnostic settings, and even the number of position states the device reports. The sensor can be configured as a dual magnetic latch, a dual unipolar switch, or a dual omnipolar switch, depending on the application.

Functional diagram of the MLX92344. 

Melexis also supports end-of-line programming, which allows fine-tuning of the MLX92344 after assembly to compensate for mechanical tolerances. For applications with tighter packaging constraints, versions with Integrated Magnetic Concentrator (IMC) technology are available, enabling lateral magnetic field sensing and providing a little more freedom in sensor and magnet placement.

Designed for Automotive Safety Applications

One of the primary target applications is seat-track position sensing. Modern automotive protection systems may sometimes require a little more detailed seat-position information to optimize airbag deployment and other safety functions. New safety requirements often call for three seat-position states rather than the traditional two-position approach.

Rather than adding additional microswitches and wiring, the MLX92344 can detect multiple seat positions using a single contactless sensor. The same approach can be applied to steering-column position sensing, which becomes increasingly important as vehicle interiors evolve toward higher levels of driving automation.

The device also targets electronic latch systems used in doors, trunks, hoods, and e-frunks. In soft-close mechanisms, engineers often need to monitor fully open, partially latched, fully latched, and over-travel conditions. The MLX92344 can identify those states using a single sensor rather than multiple mechanical switches.

Automotive-Grade Specifications

The MLX92344 operates from 2.7 V to 28 V and supports a 32-V absolute maximum rating for commercial automotive applications. The device is qualified for operation from -40°C to +150°C and is available in both TSOT23-3L surface-mount and TO92-3L through-hole packages.

The MLX92344 was developed as an ISO 26262 ASIL-B Safety Element out of Context (SEooC) and is AEC-Q100 qualified. Integrated diagnostic functions can also trigger dedicated safe-state outputs, while parallel and sequential diagnostic modes allow designers to balance magnetic update rates with diagnostic response times. Additional protection features include reverse-voltage protection, thermal protection, under-voltage reset, and ESD robustness rated at 8-kV Human Body Model and 15-kV system-level performance.

The MLX92344 gives automotive designers a way to replace multiple microswitches with a single programmable Hall-effect sensor while maintaining compatibility with existing two-wire architectures. By combining four-state position detection, programmable current outputs, integrated diagnostics, and ASIL-B development, the device addresses both the growing complexity of automotive body electronics and the increasing safety requirements driving modern vehicle designs.

All images and videos used courtesy of Melexis.