1. LT8640SIVTRPBF Substitution Conclusion From a purely electrical performance and package specification perspective, the LT8640SIVTRPBF can directly replace the LT8640SEVTRPBF, as their key parameters (input/output voltage range, output current, switching frequency, topology, etc.) and physical package (24-TFQFN) are identical. The sole critical distinction lies in the quality grade and qualification: the original part (LT8640SEV) carries the "Grade: Automotive" designation and "Qualification: AEC-Q100" certification, whereas the candidate part (LT8640SIV) lacks these markings. The LT8640SIV is an industrial/commercial grade device; its design, production testing, and reliability validation standards have not undergone the stringent automotive qualification process mandated by the Automotive Electronics Council (AEC). The feasibility of substitution depends entirely on the target application. For use in non-automotive fields such as consumer or industrial electronics, substitution is acceptable. However, for any automotive electronic system requiring AEC-Q100 certification, substitution is strictly prohibited. Using the industrial-grade part in such an application would fail to meet automotive reliability requirements and poses significant compliance risks.