EV battery current sensing

The MLX91230 and the MLX91231 from Melexis offer access to shunt or Hall type current sensor technologies. These ASIL compliant devices can measure voltage, current and temperature. Customers will be provided with flexibility and design reusability in their electric vehicle (EV) power systems.

The MLX91230, which is a conventional Hall sensor, is complemented by the MLX91231 shunt interface current sensor IC. These devices target high-voltage (HV) battery functions. Such functions include current monitoring in battery management system (BMS), battery disconnect units (BDUs), also known as battery junction boxes (BJBs), and power relay assemblies (PRAs).

The MLX91230 exhibits below 1% sensitivity drift and 100mA offset over temperature and operational lifespan. The MLX91231 has a sub-0.5% sensitivity drift with a 50 mA offset. 

By having one product family offering both shunt and Hall based current sensing, tier1s can decide which combination is the best fit for each vehicle OEM. They can easily switch from one configuration to the other if requirements change. OEMs can integrate different combinations into their vehicle models. This reusability has the benefit of minimising the engineering effort.

Designed according to the ISO 26262 functional safety standard, both current sensor devices offer full support for ASIL integration. The MLX91230 is naturally isolated, while the MLX91231 needs external isolation. Each sensor has an integrated temperature sensor as well as a dedicated safety rated overcurrent detection pin. They are housed in compact 8-pin SOIC packages.

Testing samples (B-sample) and evaluation kits are already available on demand. The MLX91230 Hall-based current sensor will be released in Q2 2023, with the MLX91231 shunt device following soon after.