The STFI7LN80K5: The 12 nC gate charge and 270 pF input capacitance at 100 V drain bias are low for an 800 V device, making it suited for hard-switching topologies like flyback and PFC converters in AC-DC power supplies, LED lighting drivers, and auxiliary power stages in industrial equipment.
STMicroelectronics has discontinued this specific MDmesh MOSFET variant, so it is no longer available through the authorized factory channel. For a BOM line already qualified to this part, the supply path is the independent distribution market — surplus inventory, overstock, or last-time-buy remnants. There is no official successor part recorded in the lifecycle data, so a replacement search should focus on pin-compatible 800 V N-channel MOSFETs in the TO-262 full-pack footprint from ST or other vendors. The date-code trace and marking consistency become critical when sourcing from the open market — the laser-etched marking on the TO-262 tab is the first check against re-marked or relabeled stock.
Ratings that drive the design decision
The 800 V Vdss gives 30% to 40% derating margin in a 400 V DC bus (typical PFC output), which is comfortable for flyback and two-switch forward converters. The 1.15 Ω Rds(on) at 10 V gate drive is moderate — expect conduction losses around 6 W at 5 A, which the 25 W package power dissipation can handle with adequate heatsinking.