Advantages and disadvantages of Schottky diodes

advantage:

SBD has the advantages of high switching frequency and reduced forward voltage, but its reverse breakdown voltage is relatively low, mostly not higher than 60V, and the highest is only about 100V, which limits its application range. Like in the switching power supply (SMPS) and power factor correction (PFC) circuit, the freewheeling diode of the power switching device, the high frequency rectifier diode of 100V or more used in the transformer secondary, the 600V～1.2kV high speed diode in the RCD snubber circuit, and For PFC boosting 600V diodes, only fast recovery epitaxial diodes (FRED) and ultra-fast recovery diodes (UFRD) are used. The reverse recovery time Trr of UFRD is also more than 20ns, which cannot meet the needs of 1MHz～3MHz SMPS in fields such as space stations. Even for SMPS with hard switching of 100kHz, due to the large conduction loss and switching loss of UFRD, the case temperature is high, and a larger heat sink is required, which increases the size and weight of SMPS, which does not meet the requirements of miniaturization and lightness. Development trend. Therefore, the development of high-voltage SBDs above 100V has always been a research topic and a hot spot of concern. In recent years, SBD has made breakthrough progress. High-voltage SBDs of 150V and 200V have been put on the market, and SBDs with more than 1kV made of new materials have also been successfully developed, thus injecting new vitality and vitality into their applications.

shortcoming:

The biggest disadvantage of Schottky diodes is that their reverse bias voltage is relatively low and the reverse leakage current is too large. For example, Schottky diodes that use silicon and metal as materials have the highest reverse bias voltage rating. To 50V, and the reverse leakage current value is a positive temperature characteristic, it is easy to increase rapidly with the increase of temperature, and it is necessary to pay attention to the hidden concern of thermal runaway in practical design. In order to avoid the above-mentioned problems, the reverse bias voltage of the Schottky diode in actual use will be much smaller than its rated value. However, the technology of Schottky diodes has also been improved, and its reverse bias voltage rating can reach up to 200V.