It is compatible with automotive and alternative mobility applications such as inverters, battery management systems (BMS) and low voltage DC-DC converters.
Power electronics designers constantly face the challenge of system size and weight in modern electric vehicles, resulting in a steady demand for smaller, lighter solutions. By eliminating the ferromagnetic concentrator, the MLX91235 gradiometric sensor occupies less space than typical current sensor technologies and eliminates measurement errors related to hysteresis. Differential measurement of the magnetic field between two internal sensing elements provides accurate current feedback and ensures the elimination of parasitic field effects. With a bandwidth of 500 kHz and a response time of 2 μs, the sensor is ideal for high-speed applications such as motor and converter control.
The MLX91235's intelligent digital architecture elevates the sensor's capabilities, ensuring high measurement accuracy and enabling the integration of several key features that enhance system development, calibration, and integration. When dealing with inherent nonlinearities, analog architectures typically rely on piecewise linear compensation. However, the MLX91235's digital architecture allows for more precise and sophisticated compensation, resulting in smoother and more accurate output. Fully digital thermal compensation further ensures that the MLX91235 delivers highly accurate measurements under all operating conditions.
The device's "open" calibration is configured via a standard serial peripheral interface (SPI), enabling on-site configuration through any microcontroller unit (MCU). Compared to coreless analog sensors, digital calibration provides a more straightforward and faster experience, allowing for easy adjustment of elements such as digital gain correction.
Integrated 16-bit overcurrent detection (OCD) enables asymmetric thresholds and includes two configurable threshold ranges. It features a configurable detection time with a minimum duration of 2 µs and an optional bounce strategy. This strategy helps avoid false positives in more stringent electromagnetic compatibility (EMC) environments. To further enhance its value, the MLX91235 also includes a 10-bit temperature feedback mechanism, enabling precise junction temperature measurement transmitted via a high-speed SPI output.
The MLX91235 meets ISO 26262 ASIL B safety element (SEoOC). Going beyond ASIL B requirements, it also incorporates a sophisticated built-in self-test function that can be activated via SPI. This function allows the sensor to report critical information such as temperature, undervoltage, and mechanical stress. Unlike conventional diagnostics, this function spans the entire signal chain, all the way to the application MCU that reads the sensor.
“Melexis has a long history in current sensing technologies, and the coreless MLX91235 is our next step,” says Bruno Boury, Product Line Manager at Melexis. This sensor offers an optimal combination of rapid on-site calibration, including OCD, compliance with ISO 26262, and high accuracy thanks to the sensor’s digital core.
Designed to meet the needs of automotive and industrial current sensing applications, the MLX91235 supports current sensing on PCBs and busbars in systems such as inverters, low-voltage DC-DC converters, chargers, electrically heated catalysts (EHC), BMS, smart pyroelectric fuses, etc.
