Smart IVT Hall and shunt sensors with external NTC input

Melexis enhances its smart IVT (current, voltage, and temperature) sensing platform by adding an NTC resistor input capability to the MLX91230 (Hall-effect) and MLX91231 (shunt interface) devices. This upgrade enables more precise external temperature measurement, complementing existing junction readings, and helps engineers address the need for comprehensive monitoring in safety-critical applications.

The integration of the NTC input into the sensors enhances the detection of variations in system temperatures. For the MLX91231 (shunt interface) in particular, it provides an additional use case of compensating the shunt resistor's residual variability over temperature, leading to a further increase in current sensing accuracy. Furthermore, the new NTC input is ASIL C compliant, permitting deployment in safety-critical automotive applications, including automotive batteries, DC fast charging, smart pyro-fuses, and power distribution modules.

The new NTC input pin allows engineers to monitor and apply post-processing to the temperature of an external component using the same IC that performs current sensing. With this expanded functionality, current, voltage, junction, and external NTC-based temperatures are all measured through a single device, streamlining development and improving system reliability. Moreover, the ASIL C functional safety compliance to ISO 26262 applies to the current, voltage, and external NTC measurement, and the diagnosable overcurrent detection (OCD). The OCD also permits direct input to the pyro-fuse driver, allowing the simple deployment of smart pyro-fuses with fewer components.

These new features complement the already extensive functionality of these sensors. Each device is equipped with an MCU complete with onboard flash memory, facilitating the deployment of custom software and enabling robust compensation of any system discrepancies. Furthermore, the LIN output option allows simple integration with 12V battery applications and power distribution modules, while UART permits direct communication with the BMS, which is starting to find its way into the Battery Disconnect Unit (BDU). For remote BMS systems, UART-over-CAN can employ a more robust physical layer while maintaining lower overhead layers above that characterise the point-to-point communication of the current sensor module to the BMS.

In addition to vehicular deployments, the expanded capabilities of the new MLX91230 and MLX91231 will also benefit other high- and low-voltage battery solutions, including BESS, solar panel installations, and e-bikes, providing precise temperature monitoring for improved system management.

With these additions, the company continues to build a comprehensive portfolio for battery applications, demonstrating our long-term commitment to this market," said Bruno Boury, product line director at Melexis. "Temperature is a critical variable as downsizing, faster charging and more demanding use cases push the systems to their thermal limits."

The new NTC input on the MLX91230 and MLX91231 provides an additional temperature data point in environments with significant thermal gradients, enabling shunt resistor DMC (data matrix code) compensation for more precise current sensing.