MOSFET, short for Metal Oxide Semiconductor Field Effect Tube, is a common power switching device used in circuit design. It is a voltage controlled device. It is characterized by gate voltage to control the drain current and has the advantages of simple driving circuit, low driving power, fast switching speed, high operating frequency and higher thermal stability than GTR. According to the conductive channel power, MOSFET can be divided into P-channel and N-channel. According to the gate voltage amplitude, it can be divided into depletion type (when the gate voltage is zero between the drain and source, there is a conductive channel) and enhancement type (gate voltage is not zero when there is a conductive channel). Power MOSFETs are mostly N-channel enhancement type.
Effective January 1, 2009, the latest version of the Technical Instructions for the Safe Transport of Dangerous Goods by Air issued by the International Civil Aviation Organization (ICAO) added UN serial numbers for dangerous goods, and lithium batteries will be classified as lithium-ion batteries (UN 3090 and UN 3091) and lithium metal batteries (UN 3480 and UN 3481). The regulation states that lithium batteries cannot be transported by air if they do not come with a test report or certificate of approval based on UN38.3.