Packaging and characteristics of Schottky diodes

Schottky diodes are divided into leaded and surface mounted (chip-on-chip) packages. Schottky diodes with leaded packages are usually used as high-frequency high-current rectifier diodes, freewheeling diodes or protection diodes. It has two packaging forms: single tube type and pair tube (dual diode) type. The Schottky pair tube has three pin lead methods: common cathode (the cathodes of the two tubes are connected), common anode (the anodes of the two tubes are connected), and series (the anode of one diode is connected to the cathode of the other diode).

The Schottky diodes that adopt surface packaging are available in single-tube, double-tube, and triple-tube types, and there are A~19 pin lead-out methods.

The main advantages of SBD include two aspects:

1. Since the Schottky barrier height is lower than the PN junction barrier height, its forward conduction threshold voltage and forward voltage drop are lower than PN junction diodes (about 0.2V lower).

2. Since SBD is a majority carrier conductive device, there are no minority carrier lifetime and reverse recovery issues. The reverse recovery time of the SBD is only the charge and discharge time of the Schottky barrier capacitor, which is completely different from the reverse recovery time of the PN junction diode. Since the reverse recovery charge of the SBD is very small, the switching speed is very fast and the switching loss is also very small, and it is especially suitable for high-frequency applications.

However, since the reverse barrier of SBD is relatively thin and breakdown occurs easily on its surface, the reverse breakdown voltage is relatively low. Since SBDs are more prone to thermal breakdown than PN junction diodes, the reverse leakage current is larger than that of PN junction diodes.