Issue & Solution

For the reasons outlined in that article, Asahi Kasei Microdevices (AKM) developed the unique coreless current sensor IC, titled “Currentier”. Currentier is the outcome of long experience and unique technology AKM has with compound semiconductor magnetic sensors (Hall elements), package design, and analog circuit design. 

Currentier is used in industrial and residential equipment around the world and contributes to meeting the following requirements:


  • Reducing system size (i.e. equipment size)
  • Reducing design man-hours
  • Creating a safer system
  • Improving system efficiency and providing more precise control

System Downsizing

In part 1, it will be explained here how Currentier can contribute to reducing system size.

Small Size

With the progress of factory automation in recent years, factories are installing more and more control equipment. Some examples of this control equipment are general-purpose drives for controlling motors, AC servo motor drives for precise position control, and controllers for robots to automate operations. A big challenge for control equipment is to increase the area efficiency of the factory by reducing the size.

That is why people have started to consider size reduction of the current detection device and peripheral circuits used for the current control of motors.  As explained in Part 1, the coreless current sensor significantly reduces the size of a system compared to the cored current sensor (Figure 2).

Figure 2. Size comparison between Coreless and Cored Current Sensors

Low Heat

Compared to the shunt method, the total size of a system is significantly smaller with a coreless current sensor, not only because the coreless current sensor needs fewer peripheral parts but also because it generates less heat and thus requires less area for heat dissipation. This is why Currentier is replacing the shunt method in many pieces of equipment.

Figure 3 shows thermal images comparing the amount of heat generated by Currentier (CZ-37xx), coreless current sensors from other company, and the shunt method.

Applied Current: 40A DC
Substrate: 70µm, 4 Layers
Thermal Image: 10 minutes after current applied
Upper Thermal Images: Red = 85°C, Blue = 25°C
Lower Thermal Images: Red = 55°C, Blue = 25°C

Figure 3. Heat generation comparison image of various current detection methods

As you can see from the thermal images, the Currentier is about 50°C lower than the shunt method and 20°C lower than other coreless current sensor. Under certain conditions, Currentier can reduce the heat dissipation area by approximately 90% compared to a 1mΩ shunt resistor, dramatically reducing the overall system size.

'Currentier' series are open-type current sensor ICs which have the world's smallest package, high accuracy, high S/N ratio, and the world's fastest response time.
With these advantages, we will offer the best current sensing solution to wide-ranging applications, such as inverter control, overcurrent detection, and electrical power detection.

* Currentier is a trademark of Asahi Kasei Microdevices Corporation.