Current sensor ICs expanded for smart power applications

Melexis has unveiled the MLX91218 Low Field (LF), the latest variant from its IMC-Hall current sensor IC. The new sensor is designed for lower current applications (below 100A). It allows smart energy monitoring in residential and small industrial power distribution units, microgrids, and EV charging cables. The non-intrusive technology is also excellent for clamp-on measurement applications.

Across industrial and residential settings, energy monitoring plays a crucial role in improving the efficiency of electronic circuits. Data captured by devices such as power supplies and Advanced Metering Infrastructure (AMI) can help drive changes in how energy is used, minimising wastage while supporting the smart management of power grids, including strategies such as peak shaving whereby consumption is lowered during peak times.

The sensor is designed to support a wide range of solutions including smart power distribution circuits, consumer units, power monitors, and power supplies, in industrial and residential settings, and other power applications, such as UPS and EV charging cables, where intelligent and non-intrusive current monitoring of up to 100A is vital for reliable operation. The sensor features a 400kHz bandwidth and 2µs response time, permitting small current changes to be detected at high speed, while the low thermal drift across a wide temperature range, high linearity (±0.5% full scale), and low noise help to ensure accurate measurement in various operating environments.

The device features a selectable analog output supporting ratiometric or fixed (Vref) mode and a flexible 3.3V or 5V power supply to ensure simple integration. Unlike core-based technologies, IMC Hall permits for the elegant vertical stacking of the current conductor, PCB, and sensing IC to ease physical design considerations. Further, the IMC design benefits embedded applications, as its surface-mount packaging simplifies sensor IC integration into larger PCBs, thereby enhancing assembly efficiency and reducing costs.

Included within the device, dual internal and external threshold over-current detection (OCD) is critical in supporting the creation of smart functions, including e-fuses, that are essential components of intelligent residential and industrial power distribution systems. An active-low open-drain output indicates OCD events and can be altered within or beyond the sensing range of the IC's output.

In a typical current sensing application, the sensor measures a bus bar or PCB current together with a simple U-shaped shield. For clamp-on current solution, the shield assembly clamps around the current wire. In some permitting applications, such as those with low EMI, it may be possible to forgo the shield to reduce integration considerations and design volume further.

"To enhance the efficiency and sustainability of power networks, intelligence is needed at a more detailed level. This is the driving force behind smart power devices in homes and industry alike, as they can reduce consumption, as well as help users to align with larger grid management strategies such as peak shaving and load shifting," said Bruno Boury, product line director at Melexis. He continued: "The new MLX91218-LF builds on 20 years of proven IMC technology to serve the critical lower current applications, ensuring straightforward integration, high accuracy, cost efficiency, and reliability."