520 V N-channel MOSFET in a full-pack TO-220 — what you need to know
There is no factory-authorized replacement with the same order code; if you need a pin-compatible substitute, the STF5NK52ZD uses the standard TO-220FP footprint shared by many ST SuperMESH™ parts in the 500 V–600 V range, but the exact die and gate charge profile differ. A cross-reference search against similar Vdss and Rds(on) ratings is the practical path for a new production allocation.
1.5 Ohm Rds(on) — what the on-resistance number means for your design
The 10 V drive voltage is the recommended gate drive to achieve the lowest on-resistance; driving the gate with a lower voltage, say 5 V, will increase Rds(on) significantly — the gate threshold voltage can be as high as 4.5 V at 50 µA, so margin at low gate drive is thin.
TO-220FP full-pack — mounting and isolation
The TO-220FP (TO-220-3 Full Pack) is a through-hole package with a fully molded, electrically isolated backside tab. Unlike a standard TO-220 where the metal tab is connected to the drain, the full-pack version lets you bolt the device directly to a grounded heatsink without an insulating washer. This simplifies assembly and reduces thermal resistance from junction to case. The three leads are formed for through-hole soldering on a standard 2.54 mm pitch. No special footprint beyond the usual TO-220 layout is needed.