Allegro releases automotive-grade current sensors, receives ISO 26262 certification

March 18, 2015 // By Christoph Hammerschmidt
Allegro MicroSystems positions its latest current sensors as a cost-effective solution without compromising accuracy, ACS724 and ACS725 AC and DC current sensors target industrial, automotive and communications applications markets. At the same time the semiconductor vendor has announced that its has completed automotive ISO 26262 process certification, issued by SGS-TÜV Saar GmbH.

The two new current sensors feature differential sensing in order to reject common-mode fields and improve accuracy in magnetically noisy environments. Internal galvanic isolation also allows the ACS724 and ACS725 to be used in high-side current sensing applications.

The ACS724 (5V) and ACS725 (3.3V) combine high accuracy with a very small SOIC8 package, making them suitable for space-constrained applications where overall costs can be reduced due to a smaller board area. Typical applications include motor control in automotive power braking applications, oil and transmission pumps, or HEV charging circuits. The sensors are also suited for load detection and management, switched-mode power supplies, and overcurrent fault protection in industrial, computer and consumer applications tied to line voltage.

Each device consists 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 inherent device accuracy is optimised through the close proximity of the magnetic field to the Hall transducer. The output of the device has a positive slope when an increasing current flows through the primary copper conduction path used for current sensing. The internal resistance of this conductive path is typically 1.2 milliohms, leading to low power losses. The terminals of the conductive path are electrically isolated from the sensor, allowing the devices to be used in high-side current sense applications without the need for high-side differential amplifiers or other costly isolation techniques.
The devices are fully calibrated prior to shipment from the factory.

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