1000 V blocking, 75 ns recovery — where it fits
The STTH110 is a 1000 V, 1 A fast-recovery epitaxial diode from STMicroelectronics, in a DO-41 axial-lead package.
Forward drop and switching loss — the thermal trade-off
At 1 A forward current the maximum forward voltage is 1.7 V, which is typical for a planar 1000 V fast-recovery die. The conduction loss at 1 A DC is 1.7 W; in a DO-41 package with 50 °C ambient the junction will rise well above 100 °C, so a continuous 1 A load needs a heatsink or forced airflow. The 75 ns trr keeps the turn-off loss manageable at 50-100 kHz switching frequencies — above that the recovery charge starts to dominate the thermal budget.
Reverse leakage at rated voltage — the high-temperature limit
Maximum reverse leakage at 1000 V is 10 µA at 25 °C, but junction temperature is the real variable. The rated maximum junction temperature is 175 °C, and leakage doubles roughly every 10 °C above 25 °C. At 125 °C junction the leakage can exceed 100 µA, which adds to the standing loss and reduces the effective blocking margin. For designs that run the diode hot, budget the leakage current into the bias network or snubber resistor.