Automotive current sensors introduced with overcurrent detection

24th June 2021
Lanna Deamer

Melexis has revealed next-generation current sensors for automotive power-conversion applications. The advantages they deliver include increased resolution, optional 3.3V or 5V operation, and integrated over-current detection circuitry.

The MLX91219 is a conventional hall current sensor. Using a ferromagnetic C-core, currents can be measured in the ranges of 200A to beyond 2000A. The MLX91218 is an IMC-Hall current sensor.

With a flexible U-shield for crosstalk immunity, currents can be measured in the ranges of 200A to 2000A. Both sensors benefit from an increased signal to noise ratio (SNR), nearly 2 times greater than preceding generations.

Featuring high linearity, within ±0.3% full scale, the AEC-Q100 automotive-qualified sensors deliver enhanced accuracy for managing high speed applications such as motor control, inverters and converters, but also redundant monitoring of Battery-Management Systems (BMS). Minimal thermal drift, maintaining electrical offset within +/-5mV and sensitivity within +/-1%, ensures accuracy over a wide temperature range.

With the option of either 3.3V or 5V operating voltage, designers can use these sensors directly in circuits containing new 3.3V low-voltage microcontrollers or with legacy 5V devices.

The MLX91218 and MLX91219 integrate Over-Current Detection (OCD) circuitry typically implemented off-chip using an external window comparator, thereby further simplifying system design, saving board space, and reducing the bill of materials.

The over-current threshold is set internally during initial product configuration. The future SOIC8 packaged products have an additional pin that allows setting the threshold voltage with increased accuracy using an external voltage divider. Two indicator pins show the overcurrent status in relation to internal and external thresholds, with 2us and 10us response times respectively.

Both sensor types provide a selectable analog output that allows the choice of a fixed output or ratiometric output that scales with the supply voltage. With 400kHz bandwidth and fast response time, they are suitable for circuits designed to operate at high switching speeds and fundamental frequencies to minimise phase delay in the control loop.

In addition, the future MLX91218 incorporates Melexis’ patented IMC integrated magnetic concentrator to optimise magnetic field shaping, which allows compact, lightweight shielding.

The MLX91219 is available in single inline (SIP) 4-pin package. The MLX91218 and the small-outline SOIC8 package for MLX91219 will be available soon.

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