Current Sensor ICs deliver Accuracy and Isolation
Allegro MicroSystems, LLC announces two new current sensor IC devices that are true ±5-A sensor ICs or uni-directional 10-A sensor ICs for use in low power applications that require higher output swings at lower current. Allegro's ACS722 and ACS723 devices provide an economical and precise solution for ac or dc current sensing in industrial, commercial, and communications systems. The small package is suited for space-constrained applications while also saving costs due to the reduced board area. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection.
These new devices consist of a precise, 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 precise, 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 and 2, to pins 3 and 4), which is the path used for current sensing. The internal resistance of this conductive path is 0.6 mΩ typical, providing low power loss.
The terminals of the conductive path are electrically isolated from the sensor leads (pins 5 through 8). This allows the ACS722 and ACS723 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. The devices are certified to 2400-Vrms isolation and can be used in ac line-tied applications.
The sensor ICs are provided in a small, low-profile surface-mount SOIC8 package. The leadframe is plated with 100% matte tin, which is compatible with standard lead-free printed circuit board assembly processes. Internally, the device is lead-free, except for flip-chip high-temperature lead-based solder balls, currently exempt from RoHS. The device is fully calibrated prior to shipment from the factory. In lots of 1,000 pieces, the unit price for these current sensors is US$1.87.
