IN Brief:
- The MLX92342 uses supply-current levels to indicate magnetic switching states and diagnostic faults over two wires.
- Melexis describes the device as an ISO 26262 ASIL B Safety Element out of Context, with response under 100 microseconds.
- A through-hole variant with an integrated capacitor supports installation without a local printed circuit board.
Melexis has introduced the MLX92342, a programmable Hall-effect switch that communicates magnetic states and diagnostic faults through a two-wire current interface. The device is intended for remote sensing points in vehicle zonal architectures and industrial equipment, including seatbelt buckles, locks and actuators where a separate signal conductor or local printed circuit board may be undesirable.
The device changes the current it draws to indicate its magnetic switching state, allowing an electronic control unit to interpret the output over the same two wires used for power. Conventional three-wire switches use separate supply, ground and signal connections. Removing a conductor can simplify the wiring arrangement, although a host circuit must be designed to distinguish the relevant current levels and respond correctly to diagnostic information.
Hall sensing provides contactless detection of a magnetic field generated by a nearby magnet. A mechanical movement changes the relative position of the magnet and sensor, allowing the electronics to interpret a switch or position state without a mechanical electrical contact at that point. The finished design still depends on the magnet’s characteristics, movement range, air gap and installation tolerances.
Melexis offers magnetic latch, unipolar switch and omnipolar switch functions within the MLX92342 family. Thresholds can be programmed to suit different magnetic arrangements, with a stated operating range from 0.5mT to 200mT for the standard configuration. An optional integrated magnetic concentrator allows lateral field detection where packaging prevents straightforward perpendicular sensing. The manufacturer specifies a narrower range of up to 40mT for that variant, so the configurations cannot be treated as electrically identical.
The MLX92342 has been developed under ISO 26262 as an ASIL B Safety Element out of Context. This describes a safety-related component developed with assumptions about its eventual use, rather than a certification of an entire vehicle function. The system manufacturer remains responsible for assessing the sensor alongside the electronic control unit, wiring, diagnostics and mechanical arrangement in the final application.
Integrated diagnostics can indicate a defined safe state through a dedicated current level. This permits the host controller to distinguish a detected device malfunction from the normal magnetic on and off states, provided its input circuit implements the required interpretation. Melexis reports that a valid output and safety indication can be delivered in less than 100 microseconds, supporting systems that need to check sensor status within short readout windows.
The device provides sequential and parallel diagnostic modes with different priorities. Sequential operation is intended for switch and end-position detection, including buckles, locks and brake fluid level sensing. Parallel operation prioritises faster magnetic updates for latch-based functions, such as motor commutation in window mechanisms and other actuators. The choice depends on the host system’s timing and fault detection requirements, not simply on a preference for the quickest stated response.
Programmable settings include switching thresholds, magnetic behaviour, output polarity, diagnostic mode, retry period and temperature compensation. Melexis also provides end-of-line programming through the supply connection using its PTC-04 programmer or Latch & Switch EVB2. This allows a sensor to be matched to an assembly after mechanical tolerances are known, without requiring a dedicated programming signal wire.
The specified supply range extends from 2.7V to 28V, and the ambient operating temperature range is -40°C to +150°C. Protective functions include reverse supply voltage protection, thermal protection and undervoltage reset. The company lists system-level electrostatic discharge robustness of 15kV for contact discharge and 25kV for indirect discharge. These device characteristics must still be assessed against the electrical environment and protective measures of the complete assembly.
Package options include TSOT23-3L for surface mounting, TO92-3L for through-hole assembly, and a TO92-3L version with an integrated capacitor that supports installation without a local PCB. The packaging distinction is material: the boardless arrangement is an available variant, not an assumption that every MLX92342 configuration can be installed without additional circuitry.
Melexis has made the MLX92342 available alongside the MLX92341, a locked, pre-programmed alternative. The new device combines sensing and diagnostic reporting at a remote endpoint, while retaining the need for system-level validation of switching thresholds, response times, electrical connections and the host controller’s treatment of faults.
