30 A fast recovery diode in DO-247 — what the ratings mean
The STTH3002W is a 30 A, 200 V fast-recovery rectifier from STMicroelectronics, built with planar technology and packaged in a DO-247 through-hole case with straight leads. Its 50 ns reverse recovery time places it in the ultrafast class, suited for continuous-current-mode boost PFC stages, output rectification in 48 V to 120 V DC-bus supplies, and snubber clamp circuits where stored charge recovery losses matter.
50 ns trr — switching loss and snubber fit
The 50 ns reverse recovery time is the headline switching parameter. In a hard-switched PFC boost stage at 100 kHz, a 30 A diode with 50 ns trr keeps the recovery charge low enough that the MOSFET turn-on loss stays manageable without a saturable-reactor snubber. The 1.05 V forward drop at 30 A is typical for a 200 V planar fast-recovery die — the conduction loss at full load is about 31.5 W, which the DO-247 package can dissipate with a heatsink and forced air.
175°C junction — thermal headroom for sustained load
Rated for a maximum junction temperature of 175°C, the STTH3002W can sustain high-current operation in confined enclosures where ambient temperatures reach 85°C or more. The 20 µA reverse leakage at 200 V, 25°C, rises with junction temperature — at 150°C the leakage may approach several milliamps, which the designer should include in the standby-loss budget for a continuously running supply.
STMicroelectronics lists the STTH3002W as obsolete.