1. Technology Type Difference The BYG20J is an avalanche diode, while the MURA260T3G is a standard fast recovery diode. When subjected to a reverse voltage exceeding 600V, the avalanche diode enters a controlled avalanche breakdown region, capable of absorbing transient high energy (typically specified by an avalanche energy rating). In contrast, a standard diode may experience uncontrolled breakdown, leading to failure. This is critical in applications with voltage spikes, such as inductive load switching or RCD clamp circuits in flyback power supplies. 2. Current Rating vs. Forward Voltage Drop Trade-off The MURA260T3G has a higher rated current (2A vs. 1.5A), theoretically offering better current-handling capability and thermal stability. However, its forward voltage drop at rated current is slightly higher (1.45V @ 2A vs. 1.4V @ 1.5A). Under an actual 1.5A operating condition, the conduction losses of the MURA260T3G may be slightly greater or comparable. Efficiency and temperature rise must be evaluated based on the specific operating point. 3. Reverse Leakage Current At a 600V reverse bias, the MURA260T3G exhibits a higher typical reverse leakage current (5µA vs. 1µA). Under high-temperature or high-voltage standby conditions, this contributes to slightly higher static power loss, potentially impacting system efficiency, especially in multi-channel parallel or high-side applications. 4. Junction Temperature Range The MURA260T3G has a wider junction temperature range (-65°C to 175°C), indicating potentially more robust thermal reliability in its die and package design. This makes it suitable for harsher environments or designs with more constrained thermal management. Engineering Recommendation: If the original design fully utilizes the avalanche characteristics of the BYG20J, substitution carries high risk. If the circuit has sufficient voltage margin (e.g., operating voltage is well below 600V and spikes are effectively suppressed) and the 2A current capability is more advantageous, substitution may be considered. However, reliability must be verified through testing.