5V fixed rail, 800 mA — TO-220 through-hole LDO
The LD1117V50C is a fixed 5V output, 800 mA low-dropout regulator from STMicroelectronics in a TO-220-3 through-hole package. Maximum dropout voltage is 1.3V at the full 800 mA load, so the input rail needs at least 6.3V to maintain regulation under worst-case conditions. Quiescent current runs 10 mA — not a micropower part, but acceptable for always-on rails where the load current dominates the thermal budget.
1.3V dropout at 800 mA — headroom and thermal reality
At 800 mA output with 1.3V dropout, the regulator dissipates about 1.04 W. The TO-220 package with a heatsink tab can handle that, but without a copper-land heatsink on the PCB the junction will climb above 125°C quickly. Protection features include over-current and over-temperature shutdown — both are the latch-off type, so a sustained short will cycle the output until the fault clears.
STMicroelectronics lists the LD1117V50C as Obsolete. The TO-220-3 footprint is standard, so a pin-compatible second-source search is practical if the volume justifies qualification.