1. Voltage Ratings - STFU15N80K5: Vdss = 800V - R6011ENX: Vdss = 600V If the original circuit's operating voltage or voltage spikes exceed 600V, the replacement risks breakdown. A 600V device is typically suitable for 230V AC input after rectification (~325V DC), whereas an 800V device is used in higher-voltage designs or where greater safety margin is required (e.g., PFC, motor drives). 2. Gate Withstand Voltage (Vgs_max) - ST: ±30V - Rohm: ±20V The R6011ENX gate is more sensitive. Voltage overshoot or noise in the original drive circuit could easily damage the gate. Ensure the absolute drive voltage remains below 20V. 3. Technology Platform & Dynamic Performance - ST uses MDmesh™ K5 superjunction technology, with a higher nominal Rds(on) test current (7A vs. 3.8A) and larger Ciss (1100pF vs. 670pF). The ST device may perform better in high-frequency switching scenarios (balancing Qg and Coss), while the Rohm device has lower input capacitance and slightly lower drive losses, but switching losses and EMI performance must be verified. 4. Current & Thermal Capability - ST: 14A / 35W, Rohm: 11A / 40W Rohm specifies higher power dissipation, but actual current capability is limited by package thermal resistance and system cooling. Under identical thermal conditions, the 11A device may require derating, especially in high-temperature environments. Additional Notes: - Substitution may be considered if the application voltage is below 450V and the gate drive voltage is under 18V, but thermal design and reliability must be re-evaluated. - There is a significant price difference, with the Rohm device being more expensive. Cost-effectiveness must be thoroughly justified before substitution.