1. Voltage & Current Ratings: The ST part is rated 650V/32A (Tc), while the Toshiba part is rated 600V/25A (Ta). The Toshiba device is inferior in both absolute voltage withstand capability and continuous current capacity compared to the ST part. In high-voltage or sustained high-current applications, the adequacy of derating must be carefully assessed, introducing a risk of reduced application margins. 2. On-Resistance (Rds(on)) & Test Conditions: ST specifies 99mΩ @ 16A/10V, whereas Toshiba specifies 140mΩ @ 7.5A/10V. Toshiba's Rds(on) is not only higher in absolute value but also tested at a lower current. This indicates that its conduction loss at higher operating currents (e.g., near its rated 25A) will be significantly greater than that of the ST part, directly impacting system efficiency and thermal dissipation. 3. Power Dissipation & Thermal Performance: Toshiba's rated Pd is 45W (Tc), higher than ST's 25W (Tc). This parameter is highly dependent on package thermal resistance and test conditions. Toshiba's "TO-220SIS" package may feature a superior thermal design, but actual thermal performance must be evaluated in conjunction with the specific heatsink and airflow. A higher rated Pd does not directly translate to cooler operation on an actual PCB. 4. Threshold Voltage & Gate Charge: Toshiba's Vgs(th) is slightly higher (4.5V vs. 4V), and its Qg is slightly larger (60nC vs. 56.5nC). This implies a marginally higher drive voltage requirement and potentially slightly slower switching speed or higher drive loss. These factors may have subtle impacts on efficiency and noise in high-frequency switching applications (e.g., SMPS). 5. Input Capacitance Test Voltage: Toshiba's Ciss is tested at 300V, while ST's is tested at 100V. Given the voltage dependency of Ciss, this discrepancy prevents a direct comparison of input capacitance values. Toshiba's actual Ciss may be lower, which indirectly influences gate drive circuit design and switching speed. Summary: The primary constraints for substitution are the reduced voltage/current ratings and the increased conduction loss. Substitution may be considered if the system operating voltage and current are well below the device ratings, a slight efficiency degradation is acceptable, and the thermal design is re-validated. Otherwise, particularly for high-voltage, high-efficiency, or high-density designs, direct substitution is not recommended.