Allegro rolls automotive-grade current sensors
The International Organisation for Standardisation (ISO) released the ISO 26262 functional safety standard in 2011 to comply with needs specific to the application sector of electrical/electronic systems within road vehicles. With the increased use of technologically complex electronics in automotive safety systems, it is critical that these systems are thoroughly designed, manufactured, validated as safe and reliable, and integrated with other systems in the automobile. Allegro claims that the creation of an active functional safety culture has become an important corporate objective within Allegro, and employees have undergone extensive training as part of the company’s commitment to the automotive market. The company announced to offer A²-SIL safety products that are quality managed as well as those that are fully compliant to the new ISO 26262 safety standard. Allegro’s safety deliverables are optimised in close co-operation with customers based on an understanding of the system safety requirements. The ISO 26262 certification has been 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 (5 V) and ACS725 (3.3 V) combine high accuracy with a very small SOIC8 package, making them ideal 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.
For more information visit www.allegromicro.com
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