1. XC6221C25A7R-G Substitution Conclusion From a core functionality perspective, the XC6221C25A7R-G can serve as a direct drop-in replacement for the original part. It provides identical fixed 2.55V/200mA output, Enable function, over-current protection, and is package-compatible. The key differences are as follows: PSRR is significantly improved from 50dB to 70dB, indicating superior rejection of high-frequency noise (e.g., at 1kHz) on the input supply, which benefits the power quality for subsequent sensitive circuits. However, the quiescent current (Iq) increases from 19µA to 50µA, raising light-load or standby power consumption by approximately 2.6 times. This is a disadvantage for applications highly sensitive to battery life. Additionally, while the nominal dropout voltage improves from 0.38V@200mA to 0.17V@100mA, the test conditions differ. Actual full-load dropout performance should be verified against the complete characteristic curves and may be similar or better. Substitution is feasible if the application demands high power-supply noise rejection and can tolerate the increased Iq. It is not suitable if ultra-low power consumption is a strict requirement.