2-wire Hall effect switches can be re-programmed

Their key attribute is the non-volatile memory that each possesses. Through this built-in EEPROM resource OEMs that have specified the MLX92242 can carry out end-of-line (EOL) programming, allowing cancellation of all mechanical tolerances within the application.

Programmable memory is used to enable the various tolerances that need defining for a specific application to be set (via the device’s V_DD pin) and if necessary readjusted, before finally being locked. The range and resolution of programmable magnetic thresholds and thermal sensitivity coefficients allows the sensor working in conjunction with a magnet to easily implement a ferrous metal proximity sensing system. The temperature compensation programmability of the MLX92242 means it can be used with all kind of magnets (including the low cost ferrite materials). The resulting cost-effective and very small ferrous proximity switch handily serves many limit position, proximity detection and encoding applications.

What differentiates the MLX92242 from other devices of this kind is that it supports 2-wire rather than a 3-wire implementation, only needing use of the V_DD and GND pins, but still providing all the necessary diagnostic capacity to respond if malfunction conditions occur. The advantage of this is that far less wiring/cable harnessing is needed, allowing deployment into confined spaces and reducing the overall weight in applications where this could otherwise be a disadvantage. The voltage range, which covers 2.7-24V, enables design flexibility to be maximised.

The MLX92242 is targeted at automotive applications, such as seatbelt latch detectors, seat position sensors, window lifters, etc. It can be implemented in remote applications, where it is some distance from the electronic control unit (ECU). A variety of industrial and security based tasks can also benefit from its use. The sophisticated proprietary offset cancellation system within the magnetic core enables faster and more precise processing of the data acquired from the sensing element while being resilient to the temperature fluctuations and other forms of stress that are inherent in automotive and industrial environments.

The device has a very high resilience to electro-static discharge (ESD) phenomena, with 8kV human body mode ESD compliance, and a broad operational temperature range which spans from -40 to +150°C. Reverse supply voltage and under-voltage lockout protection mechanisms are incorporated. It is supplied in a choice of either a 3-pin TO-92-Flat for through-hole mount assembly or in 3-pin TSOT for surface mount assembly. The MLX92242 is approximately $0.56 (USD) each for UA package and $0.54 (USD) each  for SE package versions in 10,000 unit quantities.