600 V / 8 A fast recovery in a TO-220AC insulated tab
The STTH8L06DIRG is a standard fast-recovery diode from STMicroelectronics, rated for 600 V reverse voltage and 8 A average forward current. Its 105 ns reverse recovery time places it in the fast-recovery class — suitable for continuous-conduction-mode PFC boost stages, output rectification in 400 V bus SMPS, and motor-drive snubber circuits where the recovery charge must be low enough to keep the switching transistor within its SOA.
The 105 ns reverse recovery time is the key parametric that differentiates this part from a standard 50/60 Hz rectifier. At a switching frequency of 50–100 kHz, the stored charge in the diode must be swept out fast enough to avoid cross-conduction during the dead-time of the half-bridge. A 105 ns trr at 8 A forward current means the recovery peak is sharp enough that a simple RC snubber across the diode (typically 10–47 Ω in series with 470 pF–2.2 nF) can damp the ringing without excessive dissipation.
Obsolete — sourcing through the independent channel
STMicroelectronics lists the STTH8L06DIRG as obsolete.
Thermal and mounting — the insulated tab advantage
The TO-220AC insulated package (ST's 'DIRG' suffix) has a fully isolated tab, so the heatsink can be grounded or shared across multiple devices without an insulating pad. The junction is rated for 175°C maximum, which gives headroom in a 85°C ambient industrial enclosure if the heatsink is sized for a junction-to-ambient thermal resistance below about 12°C/W at 8 A average. The forward voltage drop is 1.3 V at 8 A, so conduction loss at rated current is about 10.4 W — the heatsink must keep the junction below 175°C at that dissipation.