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Asahi Kasei Microdevices’ New Current Sensor Enables Dramatically Smaller On-Board Chargers for Electric Vehicles

Asahi Kasei Microdevices Corporation (AKM) has started mass production of the CZ39 series of coreless current sensors. The CZ39 device family is particularly well-suited to electric vehicle (EV) applications due to its 100 ns response time, low heat generation, and noise immunity. These properties are highly compatible with the silicon carbide (SiC)- and gallium nitride (GaN)- based power devices favored by OEMs for their reduced form factor and high efficiency. As such, the CZ39 series allows for the implementation of substantially smaller, lighter, and more accurate on-board charging systems for EVs.

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Asahi Kasei Microdevices’ CZ39 series coreless current sensor. (Photo: Business Wire)

Asahi Kasei Microdevices’ CZ39 series coreless current sensor. (Photo: Business Wire)

Fast current measurements

The CZ39 series features a high-sensitivity compound Hall element that enables a response time of 100 ns, making it possible for current measurements to keep up with the high switching speed of SiC- and GaN-based power solutions. This allows OEMs to take advantage of those devices’ smaller size and thus reduce the weight of on-board charging systems in order to extend cruising range. The CZ39 series’ ability to quickly signal the system to interrupt current flow during an overcurrent condition also makes for a robust electronic fuse, or e-fuse, implementation.

Reduced heat generation

AKM has developed a unique package for the CZ39 series that achieves a primary conductor resistance of only 0.3 mΩ. Even under continuous 40 Arms current flow at an ambient temperature of 125ºC, heat generation is minimal, greatly reducing the need for bulky thermal management measures. Additionally, the structure of the package provides sufficient creepage and clearance distances for use in applications above 650 V.

Enhanced noise immunity

The combination of high voltage and high-speed switching in SiC- and GaN-based systems presents a challenge with respect to electrical noise mitigation. The CZ39 family is exceptionally resilient to such conditions, ensuring continuous and highly accurate current detection even in noisy environments.

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About Asahi Kasei Microdevices (AKM)

AKM, a Japan-based company, operates an electronic components business as a member of the Asahi Kasei Group's Material sector. AKM provides customers with unique products by combining the compound semiconductor technology used in magnetic sensors with the ASIC/analog circuit technology used in silicon semiconductors. AKM's unique products and solutions are featured across a wide range of markets, including mobile communication devices and consumer products, as well as automotive electronics devices, household equipment, and industrial equipment.

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About Asahi Kasei

The Asahi Kasei Group contributes to life and living for people around the world. Since its foundation in 1922 with ammonia and cellulose fiber business, Asahi Kasei has consistently grown through the proactive transformation of its business portfolio to meet the evolving needs of every age. With more than 48,000 employees worldwide, the company contributes to sustainable society by providing solutions to the world’s challenges through its three business sectors of Material, Homes, and Health Care. For more information, visit

Asahi Kasei is also dedicated to sustainability initiatives and is contributing to reaching a carbon neutral society by 2050. To learn more, visit


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