Electronics Weekly
Called MLX91211, it is used with a ferromagnetic core around a conductor to generate an analogue output proportional to the current flowing in the cable or bus bar. The output signal has a 40kHz bandwidth and the sensor features a step response time below 10µs.
- MLX91211LUA-ABT is factory-calibrated at three temperature points enabling increased accuracy for motor control in more demanding use cases.
- MLX91211LUA-ABA is the lowest-priced variant, for applications that have lower bandwidth and lower accuracy requirements
They are both available in either TO92-3L (UA) through-hole or TSOT23-3L (SE) surface-mount packages.
“Hybrid and electric-drive architectures are being adopted in affordable e-mobility traction solutions such as two-wheel and three-wheel e-bikes, e-scooters and low-speed electric vehicles, as well as 12V/48V starter generator applications on entry-level passenger cars,” said Melexis product manager Bruno Boury. “Our MLX91211 sensor ICs now let designers create competitively priced modules by combining the high accuracy – sensitivity thermal drift is better than 1.5% – needed for a great driving experience with features tailored for economy and reliability. To date, ferromagnetic concentrator technology remains the most reliable and proven contactless current sensing technology.”
The output is an analogue voltage ratiometric to the power rail (which can range across 3.135 to 5.5V), with the ratio proportional to applied magnetic field – which meant that an ADC using the voltage rail as a reference can extract an accurate value regardless of supply voltage without using a voltage reference.
Magnetic field (and therefore current) in either direction can be sensed. Output for zero field is 50% of Vcc, min and max are 10% and 90% of Vcc. Several different sensitivity variants are available.
Power supply rejection ratio (PSRR) is 20dB (80kHz to 200kHz).
Devices are qualified to AEC-Q100 Grade 0, covering ambient temperatures from -40°C to 150°C for all automotive environments, including under the hood.
MLX91211 series is in full production. The product page is here.
