Original Part
Alternative Part
1. PS2561BL-1-F3-Q-A Substitution Conclusion
The PS2561BL-1-F3-Q-A can serve as a functionally viable substitute for the HCPL-817-30BE, with two notable deviations requiring attention: its current transfer ratio (CTR) range (100%–200%) is generally lower than that of the original part (130%–260%), and the reduced lower limit may result in diminished drive margin under weak signal conditions. Additionally, its collector-emitter saturation voltage (Vce(sat) = 300 mV) is higher than the original part’s 200 mV, implying a slight increase in conduction loss at the output stage. However, both devices align in key specifications—isolation voltage (5 kV), output current (50 mA), and package compatibility. The PS2561BL-1-F3-Q-A also offers marginally better withstand voltage (80 V) and typical forward voltage (Vf = 1.17 V). Provided the application is not sensitive to the lower CTR limit and higher saturation voltage, substitution is acceptable.
2. ISP817SMT&R Substitution Conclusion
Substitution with the ISP817SMT&R requires careful evaluation due to notable risks. Its CTR range is exceptionally wide (50%–600%) with a significantly lower minimum than the original part (130%), which may lead to poor circuit consistency and potential drive insufficiency under weak signals, possibly necessitating substantial adjustments to the current-limiting resistor. Furthermore, although it uses a 4-SMD package, its footprint width (7.62 mm) may differ from the standard 4-SMD outline of the original part—pad compatibility must be verified. On the positive side, it offers slightly higher isolation voltage (5.3 kV) and withstand voltage (80 V), while other parameters such as switching speed and Vce(sat) are largely comparable. If the application can tolerate CTR variability and mechanical compatibility is confirmed, substitution may be considered.
Analysis ID: 9B57-E830000
Based on part parameters and for reference only. Not to be used for procurement or production.
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