MLX91230 current sensors increases accuracy in a compact design
The third generation of current sensors from Melexis, the MLX91230, brings 0.5 per cent accuracy at an affordable price in a compact design, said the company. It integrates IVT measurement capability, embeds a microcontroller to offload processing from the ECU and has pre-installed safety features. The MLX91230 is intended for EV battery management and power distribution systems.
As current passing through the sensor increases, the resistance needs to go down to maintain the same thermal losses (due to the system imbalance). Similarly, designers using fluxgate technology to benefit from its galvanic isolation and high accuracy are failing to meet cost targets, as well as consuming too much power and space within the vehicle, explained Melexis. The MLX91230 addresses these challenges.
It is designed for OEMs and Tier 1s looking to reduce production costs by in-sourcing DC current sensing design. It monitors while meeting the highest functional safety requirements. For battery installations, it supports state of charge, battery state of health and state of function in both low voltage and high voltage systems. It can be used for battery management systems, battery disconnect units and battery junction boxes deployments.
The MLX91230 offers a safe and simple method of increasing capabilities in power distribution components, contactors and relays with the addition of smart functionality via the programmable flash microcontroller. Other innovative implementations include smart Pyro-Fuses, where the MLX91230 can be used to deploy local decision making, and in home energy storage systems such as solar power battery banks.
The digital infrastructure and advanced signal processing in the MLX91230 enables it to deliver “an unprecedented” one per cent accuracy over temperature and over lifetime. It exhibits 0.5 per cent accuracy over a temperature range of -40 to +125 degrees C for a one per cent lifetime drift all-in.
Melexis elaborates on this, saying that this claim is made by competing sensors but the MLX91230 guarantees this level of accuracy for thermal drift but also lifetime drift and linearity errors.
The microcontroller with on-board flash memory supports custom software deployment and extensive compensation of system imperfections. Example applications are ferromagnetic saturation onset, non-linearities and hysteresis compensation. The MCU also supports frame customisation.
The MLX91230 is AEC-Q100 and ASIL-compliant. It supports system integration up to ASIL D as per ISO 26262 functional safety requirements.
The sensor can be integrated into automotive applications, providing Hall-effect based DC current sensing for galvanic isolation from the current measurement.
Diagnosable on-chip over-current detection allows direct input to the pyro-fuse driver. There is also functional safety (SEooC) compliance which removes the burden of developing all the safety mechanisms for the designer.
Digital microcontrollers with programmable flash memory enable advanced compensations, message customisation and development of intelligent systems.
There is also an additional voltage channel which allows measurement with internal (12V/24V/48V) divider or external divider (high voltage or plausibility input). A selectable LIN or UART output enables integration with 12V battery applications and power distribution modules, as well as direct communication with battery management system or UART-over-CAN for across wire harness communication.
The MLX91230 is supplied in a compact eight-pin SOIC package.
