1. SPC5643LFF2MLQ1R Substitution Conclusion From a core hardware parameter perspective, the SPC5643LFF2MLQ1R is fully aligned with the original part in key specifications such as the processor core, operating frequency, memory capacity, package, and ADC, establishing a foundation for hardware substitution. Several critical differences exist, however. First, the supply voltage range differs. The NXP variant (3V to 5.5V) offers a wider range than the ST part (3V to 3.63V), providing greater power supply flexibility. Direct replacement requires verification that the original power design remains stable across this broader range. Second, there are modifications to the communication interfaces. The NXP part adds support for the FlexRay high-speed network but omits the original SCI interface. If the SCI was unused in the original design, this poses no issue; otherwise, communication protocol or peripheral configuration changes are mandatory. Third, differences exist in peripherals and certification data. The NXP datasheet does not explicitly list an LVD (Low-Voltage Detect) module nor denote AEC-Q100 automotive-grade qualification. The user must consult the detailed NXP datasheet to confirm the inclusion of an equivalent power monitoring function and must verify with the supplier that this specific part number has passed the necessary automotive reliability certifications—a non-negotiable prerequisite for automotive applications. In summary, provided the software layer and peripheral usage are compatible, and automotive certification is confirmed, this part can be considered a potential hardware alternative, subject to rigorous compatibility testing and software migration validation.