30 V, 3 mΩ N-channel in DPAK — what the ratings mean
The STD155N3H6 is an STMicroelectronics N-channel power MOSFET from the DeepGATE™ and STripFET™ VI series, built for low-voltage synchronous rectification, DC-DC converters, and load-switching applications where 30 V breakdown and single-digit milliohm Rds(on) matter. Gate charge of 62 nC at 10 V means the gate driver sees a moderate capacitive load; a 1 A driver can switch it in roughly 60 ns, making it usable in 100–200 kHz converters if the layout keeps the gate loop tight. That extra 25°C headroom matters for under-hood automotive or industrial enclosures where ambient hits 105°C and self-heating piles on.
STMicroelectronics lists the STD155N3H6 as obsolete. No last-time-buy window or official successor is recorded in the lifecycle data. Every lot we source gets date-code and marking verification against ST's known laser-etch font and DPAK package tooling; the laser etch on a genuine part traces cleanly to ST's plant and week code. Because the part is obsolete, a buyer should qualify a drop-in alternative if the design allows. The 30 V, 3 mΩ, DPAK footprint is a common sweet spot — several current-production ST parts and competitors' N-channel MOSFETs share the same pinout and similar gate charge.