1. MCP4018T-104E/LT Substitution Conclusion The MCP4018T-104E/LT can serve as a direct functional replacement in its core functionality. This is because it shares the same key specifications as the original AD5247BKSZ100-1RL7: a 100kΩ, 128-tap, I²C-interfaced volatile digital potentiometer with pin-to-pin compatibility. However, three critical technical differences exist. First, its operational voltage range extends down to 1.8V. This is an advantage, allowing it to function in lower system voltage rails (e.g., 1.8V-2.7V) where the original part cannot. Second, its end-to-end resistance temperature coefficient is significantly worse, degrading from 45ppm/°C to 150ppm/°C. This more than triples the sensitivity of the resistance value to ambient temperature variations, introducing greater resistance drift error in wide-temperature or high-precision applications. Third, its internal configuration is fixed in the standard three-terminal potentiometer (voltage divider) mode. In contrast, the original part was configured in a two-terminal variable resistor (rheostat) mode. It is impossible to internally short the wiper to one terminal pin to use it as a pure variable resistor. If the original circuit relies on this feature, external PCB connections must be modified. In summary, substitution is feasible in non-critical applications where the operating voltage is compatible and the circuit connection permits. However, it is not a direct drop-in replacement where temperature stability is a concern or where the original design utilizes the variable resistor mode.