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Asahi Kasei Microdevices’ new current sensor enables dramatically smaller on-board chargers for electric vehicles

February 28, 2024
Asahi Kasei Microdevices Corp.

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.

  • Asahi Kasei Microdevices’ CZ39 series coreless current sensor
    Asahi Kasei Microdevices’ CZ39 series coreless current sensor

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.

  • Mechanism of current measurement
    Mechanism of current measurement

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.

Please visit AKM.com for additional information.

  • Evolution of Asahi Kasei's current sensors
    Evolution of Asahi Kasei's current sensors