Differential current sensor ICs are economical and compact

5th April 2016

Caroline Hayes

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Two current sensor ICs from Allegro Microsystems are economical options for use in industrial, commercial, and communication systems that require very high voltage isolation, says the company.

Both the ACS724KMA (5V) and the ACS725KMA (3.3V) are available in a high-isolation, SOIC16, wide body, surface mount package that provides reinforced isolation, as well as save board space in a low profile. 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 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 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 proportional voltage is provided by the low-offset, chopper-stabilised BiCMOS Hall IC, which includes the company’s patented digital temperature compensation, resulting in 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 one to four, to pins five to eight), which is the path used for current sensing. The internal resistance of this conductive path is 0.85mΩ typical, providing low power loss.

The terminals of the conductive path are electrically isolated from the sensor leads (pins nine to 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 leadframe is plated with 100% matt tin, which is compatible with standard lead (Pb) free PCB assembly processes. Internally, the device is Pb-free. The devices are fully calibrated prior to shipment from the factory.

Allegro Microsystems: PCIM 2016 - Hall 7 - 516