Original Part
1. FOD817A3S Substitution Conclusion
The FOD817A3S is compatible with the original PS2561BL-1-F3-Q-A in basic parameters such as package, isolation voltage, and output current. However, its current transfer ratio (CTR) range is lower (80%-160% vs. 100%-200%), which may result in a weaker output signal under the same input current. This could impact signal transmission efficiency or necessitate adjustments to the drive circuit. Additionally, its maximum output voltage is lower (70V vs. 80V), limiting its suitability in high-voltage applications. On the other hand, its lower Vce saturation voltage (200mV vs. 300mV) helps reduce switching losses and improves thermal performance. If the application's operating voltage does not exceed 70V and CTR requirements can be relaxed, the FOD817A3S can serve as a viable substitute, provided the circuit's specific needs for signal gain and voltage tolerance are carefully evaluated.
2. FOD817S Substitution Conclusion
The FOD817S matches the original PS2561BL-1-F3-Q-A in package and isolation voltage. However, its current transfer ratio (CTR) range is exceptionally wide (50%-600% vs. 100%-200%). The lower minimum CTR may lead to unreliable signal transmission or require increased input current for compensation, while the higher maximum CTR risks overdriving the output. Its maximum output voltage is also lower (70V vs. 80V), restricting its use in high-voltage environments. The lower Vce saturation voltage (200mV vs. 300mV) is beneficial for power optimization. The FOD817S may only be considered as a substitute in applications with high CTR tolerance, voltage requirements not exceeding 70V, and where stable gain is not critical. Careful design is necessary to avoid performance fluctuations.
Analysis ID: 1916-5D2A000
Based on part parameters and for reference only. Not to be used for procurement or production.
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