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The Industry’s Smallest Contactless Current Sensor Featuring Minimum Power Loss from ROHM

Ultra-compact high reliability design eliminates heat generation, improving safety and energy savings in industrial equipment

The Industry’s Smallest Contactless Current Sensor

ROHM has recently announced the availability of the industry’s smallest contactless current sensor, the BM14270MUV-LB. It achieves minimum power loss (no heat generation) in an ultra-compact size, making it ideal for industrial equipment and consumer devices that detect operating conditions via current, including battery-driven drones, solar power systems, and servers in data centers requiring high power.

In recent years, the growing awareness of energy conservation and safety worldwide together with environmental regulations require safety countermeasures and power visualization in high power applications such as servers in data centers and solar power systems. This results in an increased demand for current sensors. However, conventional current sensors using Hall elements typically feature large current consumption and low sensitivity, making it necessary to draw current within the sensor itself. As such until now there were no current sensors on the market that provided high reliability and low loss in a compact form factor (3.5mm square).

ROHM developed a current sensor utilizing a high sensitivity low current MI element that allows for completely contactless current detection. The BM14270MUV-LB was developed by combining ROHM’s industry-leading semiconductor production and sensor control technologies with Aichi Steel’s MI (Magneto-Impedance) element. The result is a contactless current sensor that eliminates the need to draw current within the sensor to measure it. The sensor itself consumes very low current (0.07mA – 100x smaller than conventional products) and comes in the industry’s smallest size (3.5mm square). In addition, a disturbance magnetic field cancellation function is included to protect against noise, making shielding unnecessary. Digital output from the built-in A/D converter reduces MCU load, facilitating current monitoring. These features allow users to easily detect the current of virtually any application with high reliability, from compact battery-driven devices to high power industrial equipment.

Going forward, ROHM will continue to contribute to increase comfort and safety of the society by developing high-performance, high reliability sensors demanded by the IoT and industrial equipment markets.

Current Detection Methods (Current Sensor Types)

Availability: January 2019 (samples), April 2019 (OEM quantities)

Key Features

1. Contactless current detection achieves greater system reliability with minimum power loss

Conventional products utilizing Hall elements cannot detect current without drawing current into the sensor itself, generating both loss and heat and possibly causing system stoppage in the event the sensor fails or is damaged. In contrast, the BM14270MUV-LB enables contactless current detection by using a high sensitivity MI sensor. The result is no energy loss or heat generation even in high voltage applications, simplifying design and improving system reliability by eliminating the need for isolation.

 

2. Compact, ultra-low-current design optimized for battery-driven devices

Current Sensor Power Consumption/Loss Comparison

In conventional products, current consumed by the Hall element is large, resulting in a current consumption of around 10mA for Hall-based current sensors. On the other hand, ROHM’s latest product using MI technology achieves an industry-low current consumption of just 0.07mA (0.35mW power consumption at 5V operation) - 100x lower than conventional products. In addition, the BM14270MUV-LB is offered in an ultra-compact 3.5mm square size (vs conventional 6.0mm x 4.9mm sized products), making it ideal for battery-driven devices.

3. Built-in disturbance magnetic field cancellation function eliminates the need for shielding

Typically, in conventional products measurement error occurs due to disturbance magnetic fields, such as those due to geomagnetism (i.e. terrestrial), making it necessary to use shields to block interference. Whereas the BM14270MUV-LB includes a function that cancels disturbance magnetic fields using reciprocal wiring, allowing detection of only the magnetic field of the target current to enable high accuracy measurement without the use of shields.

Mechanism of Disturbance Magnetic Field Cancellation Function
Effects of the Disturbance Magnetic Field Cancellation Function
 

4. Digital output facilitates current detection

Digital output from the built-in A/D converter reduces MCU load when mounted in servers and other high power applications, enabling easy current detection.

 

Application Examples

  • Infrastructure such as power measurement devices, energy storage systems, solar power, and servers
  • Mechanical equipment requiring high power, including robots, FA (Factory Automation), and ACs
  • Battery-powered devices (i.e. drones)
  • Ideal for all applications requiring current monitoring.
 

Terminology

MI (Magneto-Impedance) Element

The first element in the world to use a special amorphous wire developed by Aichi Steel Corp. Designed to detect magnetic fields, it features high sensitivity detection with low power consumption. As a result, this technology is expected to be adopted in a variety of fields to accelerate IoT.