1. LP3872EMP-2.5/NOPB Substitution Conclusion The LP3872EMP-2.5/NOPB is fully compatible with the original part LP3855EMP-2.5/NOPB in core functionality (2.5V fixed output, 1.5A current, enable control, protection features) and physical package, enabling a direct pin-to-pin replacement. However, critical performance differences exist. The LP3872 exhibits a higher dropout voltage (0.55V vs. 0.44V @1.5A). Under full load, this requires a higher minimum input voltage (Vin_min ≥ Vout + 0.55V) for stable operation, imposing a stricter input voltage headroom requirement. Furthermore, the LP3872 has higher quiescent current and maximum supply current (Iq: 5mA vs. 3mA; Isupply_max: 15mA vs. 10mA). This directly results in greater power dissipation under no-load or light-load conditions, making it less suitable for efficiency-sensitive applications such as battery-powered systems. In applications with sufficient input voltage margin and no stringent quiescent current requirements, the LP3872 can serve as a direct substitute. However, in designs with low input-to-output differentials or where system standby power is a critical concern, this substitution would introduce performance degradation and requires re-evaluation.