The STMicroelectronics BYW51G-200 is a dual common-cathode fast-recovery rectifier in a D2PAK surface-mount package. It pairs two 200 V, 10 A rated diodes with a 35 ns reverse recovery time, making it suited for high-frequency switching power supplies, output rectification, and freewheeling or OR-ing diode applications where low switching loss matters.
The 35 ns reverse recovery time is the key parametric for a fast-recovery diode. In a 100 kHz forward converter or PFC boost stage, that recovery charge directly sets the turn-off loss in the diode and the turn-on stress in the companion MOSFET. A slower 200 ns part would dump several times more stored charge into the switching node, raising junction temperature and EMI. The 35 ns figure keeps recovery losses low enough that a straightforward heatsink layout on the D2PAK tab can handle 10 A average without derating into thermal runaway.
The BYW51G-200 carries an Obsolete product status. STMicroelectronics no longer manufactures this device in volume. If your design can accommodate a footprint-compatible alternative, the STMicroelectronics BYW51 series includes other current and voltage variants that may still be active — verify the specific order code against the latest ST product selector.
Package and thermal path
The D2PAK (TO-263AB) is a surface-mount package with a large metal tab that carries the common cathode connection. For a 10 A per-diode average current, the tab must be soldered to a sufficient copper area on the PCB — a minimum of 1 in² per device is a reasonable starting point for natural convection. The junction is rated to 150 °C maximum, so the thermal resistance from junction to ambient through the board footprint determines the real-world current derating.