Gate charge and switching-loss budget
The STD2N80K5: Maximum gate charge (Qg) is 3 nC at Vgs = 10 V — one of the lowest figures for an 800 V MOSFET in this current class. Combined with a typical input capacitance (Ciss) of 95 pF at Vds = 100 V, the switching losses stay low even at frequencies above 100 kHz, which is where this part earns its keep in compact flyback designs. The 4.5 Ohm on-resistance is specified at Id = 1 A and Vgs = 10 V — at 2 A the Rds(on) will be higher due to the current-dependence of the channel, so budget conduction loss using the normalized curve from the datasheet.
Thermal and temperature-grade envelope
Operating junction temperature range spans -55°C to 150°C — the full industrial temperature grade. Maximum power dissipation is 45 W at Tc = 25°C, but the DPAK's thermal resistance to ambient (RthJA) is typically 80-100°C/W on a standard FR4 footprint, so the practical dissipation in still air is well below 2 W without a heatsink. The 150°C Tj(max) matches the upper limit for most automotive and industrial-grade components.
Sourcing posture and compliance
ROHS3 compliant per the latest EU directive.