1. Voltage and Current Rating Discrepancies TK14A65W,S5X: 650V / 13.7A (Ta) FCPF260N60E: 600V / 15A (Tj) Impact: The Onsemi device is rated 50V lower. Sufficient operating voltage margin must be confirmed. The different current rating bases (Ta vs. Tj) necessitate a re-assessment of actual current-carrying capability based on the specific thermal design. 2. Dynamic Characteristics and Switching Losses Qg: 35nC (TK) vs. 62nC (FC) Ciss: 1300pF vs. 2500pF Impact: The Onsemi part exhibits significantly higher gate charge and input capacitance. This leads to higher switching losses at the same frequency, demands higher gate drive current, and may result in increased temperature rise or frequency limitations. 3. Rds(on) Test Conditions Test Current: 6.9A (TK) vs. 7.5A (FC) Impact: Although the nominal Rds(on) values are similar (250mΩ vs. 260mΩ), the differing test conditions mean conduction losses must be compared against the actual load current profile in the application. 4. Vgs Tolerance Range ±30V (TK) vs. ±20V (FC) Impact: The lower gate-source voltage tolerance of the Onsemi device requires attention to potential overvoltage risks in circuits prone to significant gate voltage ringing. 5. Technology Platform Characteristics DTMOSIV (TK) vs. SuperFET® II (FC) Impact: Both technologies aim to reduce Qg. SuperFET® II optimizes charge balance for a lower Rds(on)Qg product, while DTMOSIV focuses on reducing switching noise. Substitution may affect loop stability and EMI performance and should be verified. Recommendation: For use in switching power supplies (e.g., PFC, flyback), validate gate drive capability and high-temperature efficiency. For linear or low-speed switching applications, direct substitution is generally acceptable pending confirmation of the thermal design.