1. Current and Power Handling: The FDPF16N50UT features a continuous drain current (Id) of 15A and a maximum power dissipation (Pd) of 38.5W, both significantly higher than the STF13NK50Z's 11A and 30W. Under the same current load, the latter exhibits higher temperature rise and reduced thermal margin, representing the primary limitation for substitution. 2. On-Resistance Test Condition: While both devices share a maximum Rds(on) of 480mΩ, the FDPF16N50UT is tested at 7.5A, compared to 6.5A for the STF13NK50Z. This indirectly suggests the former likely has a larger silicon area or superior process technology, enabling it to maintain the same rated on-resistance at higher current. Its actual conduction characteristics may be superior in high-current operation. 3. Threshold Voltage: The STF13NK50Z has a maximum Vgs(th) of 4.5V, slightly lower than the FDPF16N50UT's 5V. With the same gate drive voltage, the ST part may turn on marginally earlier, but could also be slightly more noise-sensitive. Sufficiently low gate voltage must be ensured for reliable turn-off. 4. Switching Characteristics: The devices have very similar Qg and Ciss parameters, indicating comparable switching speed and losses as determined by the gate drive circuitry. Substitution compatibility is good in this regard.