The reverse recovery charge of ultrafast recovery diode is further reduced, so that its trr can be as low as tens of nanoseconds. Most of the fast recovery and ultra-fast recovery diodes below 20A are packaged in TO-220. From the internal structure, it can be divided into single tube and double tube (also known as double tube). There are two quick recovery diodes in the tube. According to the different connection methods of the two diodes, there are two types: common cathode to tube and common anode to tube.