100A current sensors target power steering and similar applications

November 01, 2016 // By Christoph Hammerschmidt
The ACS780/ACS781integrated current sensors from Allegro Microsystems Europe sense AC and DC currents up to 100 amps. Representing the highest current density of any current sensor chip from this vendor, the devices are suited for automotive and industrial environments and come in a particular slim package of just 1. millimeters.

These sensor ICs are suited for automotive, industrial and computer applications.  Automotive applications include EPS and DC/DC converters and oil and HVAC pumps that require higher currents.  Industrial applications include low side sensing in VFD and other motor control systems.  Other applications include computer servers power supply output current sensing as well as telecom inverters.

The devices are fully calibrated prior to shipment from the factory. 

The new package delivers extremely high power density for current sensing applications.  The Hall sensor technology also incorporates common-mode field rejection to optimize performance in the presence of interfering magnetic fields generated by nearby current-carrying conductors. 

The devices consist 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 optimized through the close proximity of the primary conductor to the Hall transducer and factory programming of the sensitivity and zero-ampere output voltage at the Allegro factory.

Chopper-stabilized signal path and digital temperature compensation technology also contribute to the stability of the devices across the operating temperature range.  High-level immunity to current conductor dV/dt and stray electric fields is offered through the vendor’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 has a positive slope when an increasing current flows through the primary copper conduction path, which is the path used for current sampling.

The internal resistance of this conductive path is typically 200 μΩ, providing low power loss.  The thickness of the copper conductor allows survival of the devices at high overcurrent conditions. The terminals of the conductive path are electrically isolated from the signal leads, allowing the device to operate safely with voltages up to 100 V peak on the primary conductor. 

The ACS780xLR family is lead (Pb) free. All leads