The LT3020EDD-1.8#PBF is a 100 mA positive fixed-output LDO from Analog Devices, delivering 1.8 V with a PSRR of 56 dB at 120 Hz. That 56 dB means ripple from a full-wave rectifier (100/120 Hz) is attenuated by a factor of roughly 630 — a 1 Vpp input ripple becomes about 1.6 mVpp on the output. For a 1.8 V rail feeding an analog front-end or a precision reference, that keeps the supply noise out of the signal passband.
Dropout and headroom at full load
Maximum dropout is 285 mV at 100 mA output. That sets the minimum input voltage at 2.085 V for a regulated 1.8 V rail at full current — a 3.3 V rail has 1.2 V of headroom, but a 1.8 V input rail would be marginal. The 250 µA quiescent current (Iq) is moderate; it's not a nanopower part, but for a 100 mA LDO the Iq-to-output ratio is under 0.3% at full load.
Protection and control for a power rail
On-chip protection covers over-current, over-temperature, and reverse polarity — the three common failure modes when a power rail gets miswired or shorted. The Enable pin lets a supervisor or GPIO sequence the rail on/off, which is useful for power-sequencing FPGAs or keeping a sensor supply off during sleep.