1. MAX487CSA+ Substitution Conclusion Direct substitution is not recommended. It may be considered only in specific low-speed applications with high-quality power supplies, and even then, requires careful evaluation. The primary differences between the MAX487CSA+ and the original ISL4485EIBZ-T are the data rate (250kbps vs. 20Mbps) and the supply voltage range (4.75V–5.25V vs. 4.5V–5.5V). The significant reduction in data rate renders this device unsuitable for high-speed communication applications, such as industrial high-speed buses or long-distance rapid data transfer, limiting it to low-speed scenarios only. The tighter voltage tolerance demands a more precise system power supply; otherwise, stability may be compromised. While the package is compatible and the hysteresis is identical (70mV), the critical performance parameters are severely constrained. Therefore, unless the original application operates well below 250kbps and matches the power supply requirements precisely, substitution will likely degrade system performance or cause failure.