Melexis inserts proven safety in its smart shunt solutions

Meeting functional safety requirements, this IVT (current, voltage, and temperature) device combines high accuracy with the intelligence and flexibility of a digital microcontroller unit (MCU). The MLX91231 is tailored for DC/DC converters, battery terminal sensors, low and high-voltage power distribution, and disconnection devices. 

The accurate measurement of low-voltage electronics within vehicles has always been a crucial factor for maintaining system performance and safety.

The intelligence in vehicles increases while at the same time, a greater number of low-voltage Advanced Driver Assistance System functions is added. These functions rely on low-voltage. This triggers a growing demand for high-performance, safe, and reliable current and voltage sensors.

The MLX91231 delivers excellent accuracy, featuring a lower than ±0.25% sensitivity drift error over temperature and lifetime and a 1.5μV input referred offset drift error over the same conditions. It allows closer monitoring and therefore greater optimisation of low-voltage systems, such as DC/DC converters, battery terminal sensors (BTS), and power distribution and monitoring in zonal infrastructure. The MLX91231 exhibits exceptional output stability and EMC resilience, making it ideal for deployment in even the harshest of automotive environments.

By utilising an integrated MCU, the MLX91231 delivers advanced functionalities beyond just current measurement. Supplied by a regulated 5V or directly by 12V battery, this IVT sensor provides the current, voltage, and junction temperature readout via a selectable LIN or UART output. An important feature provided by the MCU is the presence of built-in diagnosable overcurrent detection (OCD). This enables the safe and simple triggering of pyro fuses without the need to develop a complicated safety mechanism. The MLX91231 is ASIL B(D) compliant as per ISO 26262 and supports system-level integration up to ASIL D.

The custom software design of the MLX91231 is consistent with existing and future Melexis solutions. With its platform approach, Melexis provides familiarity and allows software reuse, while the availability of a dedicated solution streamlines development time and reduces costs. Furthermore, the MLX91231 features a compact 8-pin SOIC packaging which simplifies the system integration.

Bruno Boury, Product Line Manager at Melexis, says: “The new MLX91231 shunt current sensor complements our Hall-effect-based portfolio. By offering multiple sensor technologies, we clearly articulate our commitment to all DC current and power sensing applications.” He adds: “With the safety systems baked into the product, we simplify engineers’ life with regards to safety compliance.”