New High Isolation, Linear Current Sensor IC With 850 μΩ Current Conductor

Mar16_AllegroAllegro MicroSystems, LLC has announced two new current sensor ICs that are economical, high isolation solutions for AC or DC current sensing in industrial, commercial, and communications systems. Allegro’s ACS717 and ACS718 devices have a very small package that is suited for space constrained applications, though the wide-body provides the creepage and clearance needed for high isolation. Typical applications include motor control, load detection and management, switched-mode power supplies and overcurrent fault protection.

Both devices consist of a low-offset, linear Hall sensor circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which is sensed by the integrated Hall IC and converted into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic field to the Hall transducer. A proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy after packaging. The output of the device has a positive slope when an increasing current flows through the primary copper conduction path (from pins 1 through 4, to pins 5 through 8), which is the path used for current sensing. The internal resistance of this conductive path is 0.85 mΩ typical, providing low power loss.

The terminals of the conductive path are electrically isolated from the sensor leads (pins 10 through 15). This allows the ACS717 and ACS718 current sensor ICs to be used in high-side current sense applications without the use of high-side differential amplifiers or other costly isolation techniques.

Both devices are offered in a small, low profile surface mount SOICW16 package (suffix MA). The devices are lead-free with 100 percent matte tin leadframe plating and are fully calibrated prior to shipment from the factory.  These new devices are priced at $1.87 in quantities of 1,000.