BAS21TH High-Voltage Switching Diodes Nexperia BAS21TH High-Voltage Switching Diodes feature good switching speed and operate at a temperature range of -55°C to 175°C. These diodes are encapsulated in a small SOT23 (TO-236AB) Surface Mount Device (SMD) plastic package. The Nexperia BAS21TH diodes are ideally used in high-speed and general-purpose switching applications.