Linear current-sensor IC with thermal enhancement

October 30, 2013 // By Graham Prophet
ACS770 from Allegro MicroSystems Europe is a fully integrated Hall-effect based linear current sensor IC incorporating thermal enhancement for high precision.

The new device consists of a precision, low-offset linear Hall circuit with a copper conduction path located near the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage.

The total output accuracy of the ACS770 is achieved by using a new piecewise linear digital temperature compensation technique for offset and sensitivity. This greatly improves the IC’s accuracy and temperature stability without influencing the high-bandwidth (125 kHz) operation of the analogue output. Outstanding noise performance results from the use of proprietary amplifier and filter design techniques.

Device accuracy is optimised through the close proximity of the magnetic signal to the Hall transducer. A precise output voltage that is proportional to the current flowing in the conductor is provided by the low-offset chopper-stabilised BiCMOS Hall IC, which is programmed and calibrated for accuracy at the factory. Low power loss results from the fact that the internal resistance of this conductive path is typically only 100 µΩ.

Allegro’s integrated shield technology provides high-level immunity to potential interference from current variations in the conductor path and stray electric fields, resulting in low output voltage ripple and low offset drift in high-side, high-voltage applications.

The thickness of the copper conductor allows survival of the device at high overcurrent conditions. The terminals of the conductive path are electrically isolated from the signal leads, allowing the ACS770 sensor ICs to be used in applications requiring electrical isolation without the use of opto-isolators or other isolation techniques.

The device is targeted at the automotive, industrial and renewable energy markets.

The ACS770 has a heavy gauge lead frame made of oxygen-free copper and comes in a 5-pin package (suffix CB).

Allegro Microsystems; http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Fifty-To-Two-Hundred-Amp-Integrated-Conductor-Sensor-ICs/ACS770.aspx