1. XC6501C25A7R-G Substitution Conclusion Substitution is conditionally feasible, with particular attention required to whether the power supply rejection ratio (PSRR) and dropout voltage performance meet the application requirements. The XC6501C25A7R-G is fully compatible with the original part in basic specifications (input/output voltage, current, package). However, its quiescent current (Iq) is significantly reduced from 50µA to 19µA, which is beneficial for lowering system standby power consumption and extending battery life. The key differences lie in an increased dropout voltage (a maximum of 0.38V at full 200mA load, compared to 0.17V for the original part at 100mA; this remains higher even when normalized for equivalent load), resulting in a smaller stable operating margin under lower input voltages. Furthermore, the PSRR is substantially degraded from 70dB to 50dB (@1kHz), indicating a markedly poorer ability to suppress input supply ripple and noise. This degradation may lead to performance issues in analog or RF circuits with stringent power supply purity requirements. It can serve as a substitute in low-power applications where input voltage headroom is sufficient and sensitivity to supply noise is low. Otherwise, it is not recommended.