Automotive current sensors have over-current detection
Current sensors for automotive power conversion from Melexis are claimed to deliver increased resolution, optional 3.3 or 5V operation and integrated over-current detection circuitry.
There are two sensors available, the MLX91219 Hall current sensor which uses a ferromagnetic C-core to measure currents from 200 to above 2,000A, and the MLX91218, an IMC-Hall current sensor which has a flexible U-shield for crosstalk immunity to measure 200 to 2,000A. Both sensors benefit from an increased signal to noise ratio (SNR), nearly twice that of preceding generations. Linearity is high, within ±0.3 per cent full scale, which allows the AEC-Q100 automotive-qualified sensors to deliver enhanced accuracy for managing high speed applications such as motor control, inverters and converters. They can also be used for redundant monitoring of battery management systems (BMS). Minimal thermal drift, maintaining electrical offset within ±5mV and sensitivity within ± one per cent, ensures accuracy over a wide temperature range, says Melexis.
There is the option of 3.3 or 5.0V operating voltage allows designers to use the sensors directly in circuits containing new 3.3V low voltage microcontrollers or with legacy 5.0V devices.
The MLX91218 and MLX91219 integrate over-current detection (OCD) circuitry typically implemented off-chip using an external window comparator. This not only simplifies design but also saves board space and reduces the bill of materials. The over-current threshold is set internally during initial product configuration.
Both sensor types provide a selectable analogue output that allows the choice of a fixed output or ratiometric output that scales with the supply voltage. The sensors also have 400kHz bandwidth and fast response time, making them suitable for circuits designed to operate at high switching speeds and fundamental frequencies to minimise phase delay in the control loop. The 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. These will have an additional pin that allows increased accuracy in setting the threshold voltage using an external voltage divider. Two indicator pins show the over-current status in relation to internal and external thresholds, with two and 10 microseconds response times respectively.
