100 V / 20 A FERD in a DPAK — output rectifier for 48 V and 12 V rails
The ST FERD20H100SB-TR is a 100 V, 20 A Field Effect Rectifier Diode (FERD) in a DPAK (TO-252) surface-mount package. FERD technology merges PiN and Schottky characteristics to deliver a forward voltage of 705 mV at the full 20 A rating, which directly reduces conduction loss in high-current output stages. The 100 V reverse voltage provides headroom for 48 V bus converters (telecom, industrial) and 12 V OR-ing diodes in redundant power supplies. The 20 A average current rating suits single-output rectification in the 200–300 W range.
Forward voltage and switching speed — conduction vs recovery trade-off
At 20 A the maximum forward voltage is 705 mV — a low Vf for a 100 V / 20 A rectifier, which keeps junction temperature rise in check when the diode carries continuous current. The fast recovery speed (≤ 500 ns, > 200 mA) means the reverse recovery charge is low enough for hard-switched converters running at 50–100 kHz without excessive ringing. Reverse leakage is specified at 140 µA at 100 V. In a typical 48 V application the actual Vr is ~48 V, so leakage will be lower than the 100 V spec — the FERD structure trades slightly higher leakage than a pure Schottky for a softer recovery characteristic.
175 °C junction rating — thermal margin for compact designs
The maximum junction temperature is 175 °C, which is the standard for ST's power rectifier family. In a DPAK package the thermal path runs through the exposed tab to the PCB copper; a 1 oz copper pad of at least 600 mm² keeps the junction below 150 °C at 20 A with minimal airflow.