High-accuracy, high-isolation, differential current sensor ICs

Improved performance in a low profile, small footprint package

Allegro MicroSystems Europe today announced two new current sensor ICs that are economical and precise solutions for AC or DC current sensing.  These devices are ideal for use in industrial, commercial, and communication systems that require very high voltage isolation.

Both the ACS724KMA (5 V) and the ACS725KMA (3.3 V) are available in a very small package that is ideal for space-constrained applications, that also saves cost through reduced board area. They are packaged in a high-isolation SOIC16 wide body surface mount package that provides reinforced isolation. The differential sensing technology provides immunity to interfering common mode magnetic fields from adjacent current traces or motors. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection.

Both 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.  The current is sensed differentially in order to reject common-mode fields, improving accuracy in magnetically noisy environments.

The inherent device accuracy is optimised 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 includes Allegro’s patented digital temperature compensation, resulting in extremely accurate performance over temperature.

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 9 through 16). This allows the ACS724KMA current sensor IC to be used in high-side current sense applications without the use of high-side differential amplifiers or other costly isolation techniques.

The ACS724KMA and ACS725KMA are provided in a low-profile surface-mount SOIC16 package. The leadframe is plated with 100% matt tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free.  The devices are fully calibrated prior to shipment from the factory.

About Allegro

Allegro MicroSystems, LLC is a leader in developing, manufacturing and marketing high-performance semiconductors. Allegro's innovative solutions serve high-growth applications within the automotive market, with additional focus on office automation, industrial, and consumer/communications solutions. Allegro is headquartered in Worcester, Massachusetts (USA) with design, applications, and sales support centers located worldwide. Further information about Allegro can be found at www.allegromicro.com

Allegro MicroSystems Europe, headquartered in Chertsey, United Kingdom, is the European sales and marketing operation, and operates a network of representatives and distributors throughout Europe.  Allegro also has an engineering design centre in Edinburgh in Scotland and an application and marketing centre in Annecy in France.