Reinforced isolation for integrated current sensors

Melexis has announced new safety qualification (UL/IEC 62368-1) for the MLX91220 (5V) and MLX91221 (3V) current sensors. They can now be used in systems with higher voltage isolation requirements for SOIC8 (715V BI, 307V RI) and SOIC16 (1415V BI, 707V RI) packages. This upgrade extends the application range and reduces the BoM component count. Applications needing reinforced isolation include OBC and HVAC/compressor.

To ensure the safety and isolation of high voltage class 3 energy sources, such as 800V EV battery packs and chargers, two isolation barriers must be implemented to decrease it to a low risk. Until now, the devices had only been qualified as a basic (i.e. single) isolation device, mandating an engineer's need to include extra elements like an isolation amplifier into their design.

With the new UL/IEC 62368-1 certification (material group I), engineers can now use the company's Hall-effect sensors, knowing its reinforced isolation is enough to safeguard the end user from high voltage risk without additional isolation barriers. The new voltage ratings are (for a pollution degree 2): for the SOIC16 package: 1415 V for basic isolation (BI) and 707 V for reinforced isolation (RI); for the SOIC8 package, 715 V for basic isolation (BI) and 307 V for reinforced isolation (RI).

Engineers using devices with an extra isolation barrier can eradicate unnecessary isolation components. Also, designs with only basic isolation allow re-qualification as a reinforced isolated system without any change in the BoM.

Introducing this 'upgrade', solely in the form of further technical qualification, improves the value of the already well-received Hall-effect sensors, streamlining designs and reducing the associated engineering efforts and costs. This solution maintains its highly accurate, flexible, and plug-and-play nature and provides reinforced safety measures to diverse applications such as automotive OBC, DC-DC converters, high-voltage chargers, renewable energy inverters, white goods, and robotics.

"With the new MLX91220 and MLX91221 qualification, we are providing engineers with the simplest route to reinforced isolation," said Bruno Boury, product line director at Melexis. "We have effectively upgraded 50 product variants at no cost to the customer, helping them achieve critical safety requirements with just a single component – easing production costs and packaging constraints."

With its well-established reliability in automotive and industrial applications, the devices further solidify its market offering through this additional safety qualification. The current sensors come in cost-effective and miniaturised SOIC8 narrow bodies with 4mm creepage and larger SOIC16 wide-body packages with an 8mm creepage. Both devices have a bandwidth of 300kHz, a short response time of 2us, and are available with a current range between 0-50A RMS, providing a high return on investment for engineers.