ACS37220 Low-Resistance Current Sensors Allegro MicroSystems ACS37220 Low-Resistance Current Sensors are housed in a 7-pin QFN package and accurately measure currents up to 200A. The Allegro MicroSystems ACS37220 sensors offer minimal internal conductor resistance (<,100μΩ). Using two Hall plates, the devices offer common-mode field rejection and enhanced performance in the presence of external magnetic fields.