1. 140817142000 Substitution Conclusion From the perspective of core electrical parameters, this part number is a viable direct substitute. It matches the original part number exactly in all key specifications—including isolation voltage (5000Vrms), current transfer ratio (CTR: 50%-600% @5mA), output capability (35V, 50mA), and saturation voltage (200mV)—ensuring functional equivalence for basic isolation and signal transmission. Two minor discrepancies exist. First, there is a slight variation in the package description: the original is listed as "4-SMD," while this part is described as "4-DIP-S" (though its parameter table notes "4-SMD, Gull Wing"). It is necessary to verify that the package outline, lead pitch, and dimensions are identical by reviewing the mechanical drawings in the manufacturer's datasheet. Second, the typical forward voltage (Vf) shifts from 1.2V to 1.24V. This 0.04V increase will cause a negligible reduction in LED drive current under the same input current-limiting resistor, with no appreciable impact on CTR or circuit functionality. Therefore, substitution is acceptable once mechanical package compatibility is confirmed.