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Melexis MLX9122x Hall-Effect Current Sensors

Cuts response time to 2µs for use in high-frequency switching power converters

The Melexis 5V MLX91220 and 3.3V MLX91221 are Hall-effect current sensors which integrate a sensing element, signal conditioning and voltage isolation in a single device. These Melexis second-generation isolated integrated AC and DC current sensors provide engineers with greater design flexibility and improved performance.

The MLX91220/21 sensors feature higher bandwidth of 300kHz than Melexis’ first-generation integrated current sensors. This produces a faster response time of 2μs, enabling the sensor to support higher switching frequencies and more accurate tracking in a power converter’s control loop.

Because the MLX91220/21 implements internal differential magnetic sensing rather than relying on ferromagnetic concentrators, it provides a high level of stray field immunity. It can therefore be included in higher-density power electronics systems, as the sensor is less affected by stray magnetic fields from nearby components.

The MLX91220/21 also offers improved dual on-chip Over-Current Detection (OCD) capability, enabling concurrent internal and external over-current monitoring. The internal OCD threshold can be selected in- or out-of-range, with a response time of 2µs. An external reference voltage threshold can also be set, within or close to the output operating range. This has a typical response time of 10µs. Both can be used in one application for redundant operation, or to detect separately a short circuit and out-of-specification conditions.

The output modes for these plug-and-play sensors are flexible. Customers have a choice between ratiometric analog output voltages, as preferred by the automotive industry, or fixed reference voltages. The output mode is selected when ordering, and then factory trimmed.

MLX91220/21 Features

  • SOIC-8 narrow body or SOIC-16 wide body package
  • Low internal ohmic losses
    • 0.9mΩ for SOIC-8 package
    • 0.75mΩ for SOIC-16 package
  • Rated voltage isolation:
    • 2.4kVrms for SOIC-8
    • 4.8kVrms for SOIC-16
  • AEC-Q100 qualified

MLX91220/21 Applications

  • Automotive:
    • Onboard chargers
    • DC-DC converters
    • PTC heaters
    • E-compressors
    • Electric motors
  • Small electric drives
  • DC-DC converters
  • Solar inverters
  • Power supplies
  • Electrical vehicle charging equipment
  • White goods
  • Demand/load control

Development Kit

The Melexis DVK91220 development kit provides all the components needed to evaluate the performance and the functionality of the MLX91220 and MLX91221 integrated current sensors.

It is supplied with an isolated current measurement demonstration factory-calibrated for 50A operation.