The STTH3R06U is a standard fast-recovery rectifier diode from STMicroelectronics, rated for 600 V reverse voltage and 3 A average forward current. Its 35 ns reverse recovery time makes it suitable for high-frequency switching applications like power factor correction (PFC) circuits, freewheeling diodes in motor drives, and snubber networks in switch-mode power supplies. Packaged in a DO-214AA (SMB) surface-mount case, it fits standard reflow assembly processes.
The 35 ns reverse recovery time is the key parameter for this diode. In a continuous-conduction-mode PFC boost stage, a slower diode would cause excessive turn-on loss in the MOSFET and higher EMI. The STTH3R06U's 35 ns trr keeps the recovery current spike short, letting the designer use a smaller snubber or even skip it in a well-laid-out 100 kHz design. The fast recovery characteristic is maintained across the full junction temperature range up to 175°C.
Forward voltage and conduction loss budget
At 1.7 V maximum forward drop at 3 A, the STTH3R06U's conduction loss runs about 5.1 W peak. That figure drives the thermal design: the DO-214AA package relies on the PCB copper for heat spreading. For continuous 3 A operation, a minimum 1 oz copper pad with thermal vias to an inner plane is recommended to keep the junction below 175°C.