AMR-based current sensor delivers high accuracy, wide bandwidth

By Gina Roos, editor-in-chief

ACEINNA  claimed the industry’s first high-accuracy, wide-bandwidth anisotropic magneto resistive (AMR)-based current sensor, targeting a wide range of industrial and power supply applications. The new MCx1101 family of ±5-A, ±20-A, and ±50-A current sensors tout much higher DC accuracy and dynamic range compared with alternative solutions. As an example, the ±20-A version provides a typical accuracy of ±0.6% and is guaranteed to achieve an accuracy of ±2.0% (max) at 85°C.

The fully integrated, bi-directional current sensors also guarantee an offset of ±60 mA, or ±0.3% of FSR (max) over temperature. This means that high accuracy can be achieved over a roughly 10:1 range of currents, which is approximately a 10× improvement in dynamic range versus leading Hall-sensor−based devices, said ACEINNA.

Thanks to the high-accuracy, 1.5-MHz signal bandwidth with industry benchmark phase shift versus frequency and 4.8-kV isolation, the AMR current sensors are suited for high- and low-side sensing in fast current control loops for high-performance power supplies, inverters, and motor control applications.

The fast response and high bandwidth also make the MCx110a family suited for fast switching SiC- and GaN-based power stages. Other key specs include an output step response time of 0.3 µs, an overcurrent response time of 0.2 µs, and an integrated overcurrent detection flag to help implement overcurrent protection (OCP).

AMR technology offers several advantages compared to other current-sensing approaches including Hall, current transformer (CT), and shunt resistors, according to ACEINNA. AMR offers significantly higher bandwidth and dynamic range compared to Hall-based current sensors and delivers a smaller size and reduced cost compared to current sensors. As a fully integrated solution, AMR eliminates the need for an external amplifier and related circuitry needed for high-voltage isolation — a challenge at high frequencies — compared to shunt resistors, the company added.

“In addition, shunt resistors require enough IR drop to achieve accuracy goals at the low end of the current range, which often means they are dissipating undesirable levels of power at nominal currents,” said ACEINNA. “By contrast, the AMR device only measures the magnetic field generated by the current, so the I² R losses can be minimized.”

The family is offered in both fixed-gain (MCA1101) and ratiometric-gain (MCR1101) versions. The current sensors are packaged in an industry-standard SOIC-16 package with a low-impedance (0.9 mΩ) current path and is certified by UL/IEC/EN for isolated applications.

These devices can be used in a wide range of applications including inverters, motor control, industrial robots, manufacturing systems, telecom and server farm power supplies, electric vehicle charging stations, IoT appliances, and home automation.

The MCx1101 family, including evaluation boards, is available now for sampling and volume shipments. The parts can be ordered at Mouser.