Melexis MLX91235 Coreless Technology

Global microelectronics engineering company Melexis has announced the launch of its new current sensor chip - MLX91235. Specifically designed for automotive and alternative mobility applications, this product offers broad support for various scenarios including inverters, Battery Management Systems (BMS), and the low-voltage side of DC-DC converters. Power electronics designers in the modern Electric Vehicle (EV) sector continuously face challenges related to system size and weight, with a pressing need for smaller and lighter solutions. Melexis' gradient measurement sensor, the MLX91235, achieves a more compact design compared to traditional current sensor technologies by eliminating the magnetic core that concentrates magnetic fields, effectively eliminating measurement errors caused by hysteresis. Utilizing a differential magnetic field measurement technique between two internal sensing elements, the sensor not only provides high-precision current feedback but also effectively mitigates the influence of stray magnetic fields. With a bandwidth of 500kHz and a response time of just 2 microseconds, the MLX91235 also demonstrates exceptional performance in high-speed applications such as motor control and converters.

The MLX91235 features an intelligent digital architecture that ensures excellent measurement accuracy while enhancing sensor performance and integrating multiple key functions, significantly boosting efficiency in development, calibration, and system integration. Compared to the segmented linear compensation methods commonly used in analog architectures, the digital architecture of the MLX91235 demonstrates greater capability in handling inherent nonlinear characteristics, enabling more precise and advanced compensation strategies to output more accurate and smooth data. Furthermore, the sensor employs fully digital temperature compensation technology to further ensure high-precision measurements across the entire operating range.

The MLX91235 adopts an "open" calibration design, configured via a standard Serial Peripheral Interface (SPI), allowing any Microcontroller Unit (MCU) to easily perform online calibration. Compared to analog coreless sensors, the digital calibration method of this device is more intuitive and efficient, enabling easy adjustment of parameters such as digital gain correction, thereby greatly enhancing calibration flexibility and efficiency. The MLX91235 is equipped with a 16-bit Over Current Detection (OCD) function, supporting asymmetric threshold settings and providing two freely configurable threshold ranges. Additionally, this function features a configurable detection time with a minimum of 2 microseconds and the option to apply a strategy to prevent false positives, effectively reducing misalarms in environments with poor Electromagnetic Compatibility (EMC). The sensor also integrates a 10-bit temperature feedback mechanism, capable of accurately outputting junction temperature measurements through a high-speed SPI interface.

The MLX91235 complies with the ISO 26262 standard and is certified as a Safety Element out of Context (SEooC) for ASIL B level. In addition to meeting the stringent requirements of ASIL B, the sensor also incorporates an advanced self-test function that can be easily triggered via the SPI interface. This self-test function comprehensively monitors and reports multiple key parameter information, including temperature, undervoltage, and mechanical stress. Notably, compared to traditional diagnostic methods, this self-test function covers the entire signal chain from the sensor to the application MCU. Bruno Boury, Director of Product Lines at Melexis, stated, "Melexis has a long history in sensor technology, and the coreless sensor MLX91235 is a star in our new generation of products." He further explained, "This sensor combines online rapid calibration, OCD functionality, ISO 26262 compliance, and high precision enabled by its digital core. These outstanding features, combined with the comprehensive support we provide to customers, are key to Melexis' successful introduction of this new technology into the field." The MLX91235 is tailored for current sensing applications in automotive and industrial sectors, widely applicable to PCB and busbar current sensing in systems such as inverters, low-voltage DC-DC converters, chargers, Electric Heated Catalysts (EHCs), Battery Management Systems (BMS), and smart thermal fuses.