Allegro Microsystems recently announced two current sensors to address the evolving market needs of electric vehicles, renewable energy systems, and data centers.
Allegro’s new current sensors.
While traditional shunt-based current sensing methods are reliable, they often fall short of meeting the increased requirements of modern power electronics systems. These conventional approaches typically involve external sense resistors and operational amplifiers, which can introduce power losses, increase component count, and consume valuable board space. Allegro Microsystems designed its integrated Hall-effect-based current sensors, the ACS37220 and ACS37041, to “redefine magnetic current sensing”.
The ACS37220
The ACS37220 is a highly precise, integrated current sensor designed for applications including EV DC-DC converters, clean energy storage, and data center power supplies.
The sensor employs a differential Hall-effect sensing architecture with two Hall plates to provide common-mode field rejection and optimized performance in external magnetic fields. The device provides a ratiometric analog output voltage proportional to the sensed current and can operate from either a 3.3-V or 5-V supply with corresponding output voltage ranges. With this architecture, it offers a wide current sensing range from ±100 A to ±200 A, depending on the specific variant. Coming in a seven-pin QFN package with a small 4 mm x 4 mm footprint, the sensor also boasts an ultra-low internal conductor resistance of less than 100 μΩ.
Functional block diagram of the ACS37220.
The ACS37220 also includes a bandwidth of 150 kHz, a maximum response time of 4 μs, and a sensitivity ranging from 8.8 mV/A to 20 mV/A, depending on the variant. The sensitivity error is kept to a maximum of ±3.1%, while the quiescent voltage output error is limited to ±10 mV max. It can operate across a wide temperature range from -40°C to 150°C.
Typical application circuit employing the ACS37220.
The ACS37220 is factory-calibrated for high accuracy over the full temperature range and offers 100-V RMS functional isolation. It is also qualified to AEC-Q100 Grade 0 automotive standards. Designers can adjust overcurrent fault output with a configurable threshold between 50% and 200% of the full-scale range, set via an external resistor or voltage on the VOC pin. The device also incorporates digital temperature compensation circuitry for enhanced accuracy.
The ACS37041
The ACS37041 is an advanced, fully integrated Hall-effect-based current sensor IC built for precise current measurement in a compact form factor. Housed in a space-efficient SOT23-W five-pin LH package, the sensor is designed for applications including industrial motor drives and clean energy inverters.
The ACS37041 stands out for its shuntless design, which eliminates the need for external sense resistors and op amps typically required in traditional current sensing solutions. This self-contained approach significantly reduces component count and simplifies system design while also minimizing power losses associated with external shunt resistors. The sensor also incorporates an integrated conductor with exceptionally low resistance—less than 1 mΩ—which further contributes to system efficiency by minimizing power dissipation. This low-resistance path enables current measurements up to 30 A.
Rendering of the ACS37041.
The ACS37041 uses a differential sensing technique with two Hall plates to effectively reject common-mode magnetic fields. Using this architecture, the ACS37041 outputs a voltage signal proportional to the sensed current and features bandwidth up to 125 kHz. This architecture also provides the ACS37041 with inherent galvanic isolation, including functional isolation for rails up to 100 V.
Promising Alternatives to Traditional Shunts
With the introduction of the ACS37220 and ACS37041, Allegro Microsystems aims to provide an alternative to traditional shunts. The new current sensors pack the utility of a shunt amplifier, shunt resistor, and passive components into a small, single package. Their low heat dissipation, simplified design, and integrated packaging make the ACS37220 a promising candidate for high-current monitoring applications up to 200 A and the ACS37041 a strong option for current sensing applications up to 30 A.
All images used courtesy of Allegro Microsystems.
