600 V blocking, 5 A continuous — the offline power switch
The STP5NK60Z is an N-channel 600 V, 5 A power MOSFET from ST's SuperMESH™ series, housed in a through-hole TO-220-3 package. It is built for offline AC-DC converters, flyback and PFC stages, and motor-drive auxiliary supplies where the 600 V drain-source rating provides headroom for universal-input rectified DC (typically 375 V nominal) plus switching spikes.
1.6 Ohm on-resistance — conduction loss at the operating point
Rds(on) is specified at 1.6 Ohm maximum with Vgs = 10 V and Id = 2.5 A. At the full 5 A continuous rating, the conduction loss reaches I²R = 40 W (using the 1.6 Ohm ceiling), which must be dissipated within the 90 W package limit at Tc = 25 °C. Real-world heatsink sizing should budget for the Rds(on) increase with junction temperature — the datasheet's normalised curve shows approximately 1.5× at 125 °C Tj.
34 nC gate charge — drive current budget
Total gate charge Qg is 34 nC at Vgs = 10 V. The input capacitance Ciss is 690 pF at Vds = 25 V, which influences the turn-on delay and the driver's peak current requirement for fast edges.
The -55°C low end qualifies the part for avionics cold-soak, outdoor telecom cabinets in arctic climates, and military power supplies. The 150°C Tj(max) is typical for TO-220 power devices, but continuous operation above 100°C requires derating of the 90 W power dissipation per the datasheet's thermal curves.