Post-switcher noise rejection for sensitive analog rails
The LP3871ES-2.5/NOPB is a fixed 2.5 V output LDO from Texas Instruments, delivering up to 800 mA with a maximum dropout voltage of 0.35 V at full load — the headroom between the input rail and 2.5 V must stay above 0.35 V across the load range to maintain regulation. Its PSRR spans 73 dB to 57 dB at 120 Hz, meaning it attenuates the 100/120 Hz ripple from a preceding switching regulator or rectifier by that margin — critical for powering analog front-ends, ADCs, or precision references where supply noise couples into the signal path.
Package, temperature grade, and control features
Housed in a DDPAK/TO-263-5 surface-mount package (5 leads plus exposed tab), the LP3871ES-2.5/NOPB requires a thermal pad on the PCB to sink heat from the die — the tab is the primary thermal path, so the board copper area under it sets the effective RθJA. An Enable pin allows the output to be shut down, and integrated protection covers over-current, over-temperature, and short-circuit events.