1. Technology Generation & Core Performance: The IPP50R250CPXKSA1 utilizes Infineon CoolMOS™ technology, while the FDP18N50 is based on Onsemi UniFET™. The core difference manifests in switching losses: the gate charge (Qg: 36nC) of the IP part is only 60% of the F part (60nC), and its input capacitance (Ciss) is approximately 50% lower. In high-frequency applications like switching power supplies, the IP part achieves faster switching speed, significantly reduced turn-on/turn-off losses, and consequently higher overall system efficiency. 2. Current & Power Handling Capability: The continuous drain current (Id: 18A) and maximum power dissipation (235W) of the FDP18N50 are substantially higher than those of the IPP50R250CPXKSA1 (13A, 114W). This is not merely a numerical difference; it indicates that the F part features a larger die area and/or superior thermal resistance, enabling it to withstand higher steady-state current and power stress. Direct replacement with the IP part in applications operating near the original design's current limit or with poor thermal management carries a risk of overheating and failure. 3. Gate Drive Characteristics: The IP part has a lower gate threshold voltage Vgs(th) (3.5V vs. 5V) and a lower maximum Vgs tolerance (±20V vs. ±30V). The IP part is easier to turn on but is more sensitive to voltage overshoot on the gate drive. In contrast, the F part requires a higher drive voltage to ensure full conduction but offers a greater design margin for the driver. When considering a direct swap, it is essential to verify that the drive circuit voltage remains within ±20V. Summary: If the application's peak current is well below 13A, operates at high frequency, and prioritizes efficiency, the IPP50R250CPXKSA1 represents an upgrade over the FDP18N50. However, if the application emphasizes operation in the linear region, high continuous current capability, or harsh thermal environments, the FDP18N50 remains more suitable. A re-evaluation based on the actual operating current waveform and temperature rise is mandatory.