The latest family of fully integrated current sensor ICs

27th March 2018
Enaie Azambuja

Allegro MicroSystems Europe has announced a new family of current sensor ICs that provide economical and precise solutions for AC or DC current sensing. A 200kHz bandwidth makes it suitable for motor control, load detection and management, power supply and DC/DC converter control, as well as inverter control. The 2.5µs response time enables overcurrent fault detection in safety-critical applications.

This family can be used in automotive and industrial applications with an accuracy of +/- 2.1% over the lifetime of the IC. Both current sensor ICs work off of a single supply 5V (ACS772) and 3.3V (ACS773).

The 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.

Device accuracy is optimised through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional output voltage is provided by the low-offset, chopper-stabilised BiCMOS Hall IC, which is programmed for accuracy at the factory. Proprietary digital temperature compensation technology greatly improves the IC accuracy and temperature stability.

High-level immunity to current conductor dV/dt and stray electric fields is offered by Allegro’s proprietary integrated shield technology for low output voltage ripple and low offset drift in high-side, high-voltage applications.

The output of the device increases when an increasing current flows through the primary copper conduction path (from terminal 4 to terminal 5), which is the path used for current sampling. The internal resistance of this conductive path is 100μΩ typical, providing low power loss. 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 (pins 1 through 3). This allows the ACS772 family of sensor ICs to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.

The ACS722 and ACS733 current sensor ICs are provided in an Allegro custom CB package that provides a very small form footprint over current sensor modules offered by competing solutions.

These devices also offer a 2.5uS response time, which is the fastest response time of an IC ever offered in the custom Allegro CB package. It is fully calibrated prior to shipment from the factory and is lead (Pb) free. All leads are plated with 100% matt-tin, and there is no Pb inside the package. The heavy gauge leadframe is made of oxygen-free copper.

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