New Industry Products

Anisotropic Magneto Resistive Current Sensors Handle up to ±50A

February 27, 2019 by Scott McMahan

Aceinna announced its new MCx1101 family of ±5A, ±20A, and ±50A current sensors for industrial and power supply applications. The company claims that the family is the first high-accuracy wide-bandwidth Anisotropic Magneto Resistive (AMR) based current sensors on the market.

The broad range of applications for the current sensors include servers, telecom, and industrial power supplies. The current sensors are also suitable for power aggregation, over-current protection; dynamic current sensing in feedback loops; PFC and inverter control; motor control loops and protection.

Additional applications include automation, robotics, and servo systems; automotive and EV power systems; solar inverters and optimizers; grid-tie and storage current monitoring; MPPT circuit current monitoring; central inverter current monitoring; consumer; motor balance and remote device monitoring; home automation control and IoT remote sensing. (See typical application block diagram above).

"Our new integrated, AMR-based Current Sensor family provides the best performance for the price in the industry," says Khagendra Thapa, VP Current Sensor Product for Aceinna. "There are other AMR based current sensing solutions on the market, but they require a great deal of integration to make them work. Ours are plug and play."

The MCx1101 are fully integrated, bi-directional current sensors that deliver much higher dc accuracy and dynamic range compared to alternative solutions. For example, the ±20A version has a typical accuracy of ±0.6% and is guaranteed to achieve an accuracy of ±2.0% (max) at 85°C.

These new current sensors also guarantee an offset of ±60mA, or ±0.3% of FSR (max) over temperature, which means that high accuracy can be achieved over a roughly 10:1 range of currents. This is a roughly 10x improvement in dynamic range vs. leading Hall-sensor-based devices.

According to Aceinna, these devices deliver a unique combination of high accuracy, 1.5MHz signal bandwidth with industry benchmark phase shift vs. frequency and 4.8kV isolation. This combination makes them suitable 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 of the MCx1101 can also enable fast switching SiC- and GaN-based power stages that use smaller components and higher speeds that take advantage of wide-bandgap switches. Output step response time is 0.3µs. The MCx1101 also provides an integrated over current detection flag to help implement the over-current protection required in modern power systems. Over-current detection response time is 0.2µs.

The family includes ±50A, ±20A, and ±5A ranges, and is available in both fixed gain (MCA1101) and ratiometric gain (MCR1101) versions. It is packaged in an industry standard SOIC-16 package with a low impedance (0.9mΩ) current path, and is certified by UL/IEC/EN for isolated applications.

The company points out that AMR technology has notable advantages compared other approaches such as Hall, current transformers (CTs), and shunt resistors. First, compared to Hall-based current sensors, AMR provides significantly higher bandwidth and dynamic range, and compared with CT's, AMR offers reduced size and cost, as well as response to dc.

Unlike a shunt resistor, AMR provides a fully integrated solution, eliminating the external amplifier and related circuitry required for high voltage isolation, which is a significant challenge at high frequencies. Shunt resistors also require enough IR drop to achieve accuracy goals at the low end of the current range, which often means they are dissipating unacceptable levels of power at nominal currents.

By contrast, the AMR device only measures the magnetic field generated by the current. So, the I2R losses can be minimized.

Electronic and electrical power systems drawing over 75W generally require power factor correction and power factor correction pushes up the voltage, speed, and complexity of power systems. In such designs, fast, isolated current measurement is needed. The company says that wide bandwidth and speed are crucial in achieving the higher switching frequencies everyone wants but can't easily attain.

Features of AMR-based integrated current sensors

  • Superior range & accuracy
  • 0.6% Typical total error @25°C
  • (MCA1101-20-5)
  • 2.0% Max error over temperature (MCA1101-20-5)
  • Superior frequency response
  • 1.5MHz (typical 3dB BW)
  • Fast output response time (300ns typical)
  • Low primary resistance (0.9mΩ)
  • Single 5V supply operation
  • Low power consumption (8mA typical)
  • Zero-current reference Pin (Vref)
  • Overcurrent fault detection
  • SOIC-16 package (RoHS/REACH compliant)
  • -40°C to +105°C Operating temperature range
  • UL/IEC/EN60950-1 Certified
  • 4.8kV Dielectric Strength Voltage
  • 1097VRMS basic isolation Voltage
  • 400VRMS reinforced isolation Voltage

Units and evaluation boards are available now for sampling and volume shipments.