The LD1117DT18C is officially obsolete per the manufacturer lifecycle record.
Fixed 1.8V output, 800mA capacity
This is a single-output positive LDO regulator from ST's LD1117 family, providing a fixed 1.8V rail at up to 800mA continuous output. Maximum dropout voltage is 1.3V at full load, meaning the input rail must stay above 3.1V to maintain regulation — a key headroom check for 3.3V or 5V bus-derived supplies. Quiescent current is 10 mA typical; this is not a low-Iq part for battery-standby designs but is acceptable for always-on board-level regulation where the load current dominates the power budget.
PSRR and protection features
Power supply rejection ratio is 75 dB at 120 Hz, providing effective ripple attenuation on rectified line-frequency supplies — relevant for industrial or audio-stage pre-regulation where the input bus carries residual mains hum. Built-in over-current and over-temperature protection allow the regulator to survive output shorts or thermal overload without external clamp diodes.
DPAK package and temperature grade
The tab is the output terminal — layout must connect it to the output rail with adequate copper area for thermal dissipation at 800 mA.