Technical Description

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

Improving System Efficiency

In part 4, it will be explained her how Currentier can contribute to improving system efficiency and providing more precise control.

In recent years, with increasing interest in the environment, improving the efficiency of industrial and residential equipment has become a major issue. Attention has been paid to the power-factor correction (PFC) circuit. In the past, control ICs for PFCs were widely used, but recently, in order to achieve even higher efficiency, circuits composed of discrete components such as totem pole PFCs have been adopted. For example, in multi air conditioners, commercial air conditioners, and room air conditioners, Annual Performance Factor (APF) values, Coefficient Of Performance (COP) values, and Integrated Part Load Value (IPLV) values that represent efficiency are regarded as important. To improve these values, new development of the above PFC circuit is underway.

The challenge is to control the current of the PFC circuit. In order to improve efficiency, it is necessary to precisely detect and control the current without depending on ambient temperature fluctuations. However, in the shunt method, characteristic fluctuations due to ambient temperature fluctuations need to be corrected by peripheral components, which increases the number of steps required for verification, the circuit scale, and the cost of components.

(Refer to part 1 and part 2 for details) 

Also, the cored current sensor is said to have high accuracy among current sensors, has the problem of increasing cost and size.

(Refer to, “Types and Characteristics of Current Sensors” for details)

Currentier achieves temperature characteristics with overall accuracy comparable to the cored current sensor, despite the coreless current sensor (Figure 1). High accuracy PFC current control can improve the efficiency of the whole system and can solve the above cost and size issues as well.

Figure 1. Temperature characteristics comparison between Currentier and competitor

For industrial equipment such as AC servo motor drives, it is important to achieve more precise control in addition to efficiency. The issue is the noise characteristic Signal Noise Ratio (SNR) of the current detector.

Currentier applies AKM's ultra-sensitive compound Hall element technology to achieve a noise characteristic of 3mArms (equivalent to ENOB 14-bit) in a 200kHz bandwidth. This has noise characteristics that are about 10 times better than conventional competitive current sensors, enabling more precise control of equipment (Figure 2).

Figure 2. Noise characteristics comparison between Currentier AK31xx and competing current sensors

In next part, it will be explained AKM’s technical details to realize coreless current sensor IC, Currentier.

'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.