5V fixed LDO, 800 mA, DPAK — the rail decision
The LD1117DT50CTR is a positive fixed-output LDO regulator delivering 5V at up to 800 mA continuous from a maximum input of 15V. The 1.3V maximum dropout at 800 mA means the input rail needs at least 6.3V to hold regulation under full load — budget that headroom in your supply chain. With a PSRR of 75 dB at 120 Hz, this part provides meaningful ripple rejection for post-rectifier filtering or noise-sensitive 5V analog rails. The DPAK (TO-252-3) package with exposed tab lets the PCB copper plane sink heat; the 125°C junction rating supports industrial or under-hood environments without derating the output current.
Dropout, quiescent current, and protection
The 1.3V maximum dropout at 800 mA is the headroom number to design to; typical dropout is lower but the max guarantees regulation across temperature and unit variation. Quiescent current is 10 mA — not ultra-low-power, but acceptable for always-on industrial rails where the 5V bus is never shut down. Built-in over-current and over-temperature protection fold back the output under fault conditions; the regulator recovers automatically when the fault clears, which simplifies the protection scheme on the board.
Active production, DPAK availability
ROHS3 compliant per. The DPAK package is a common footprint with broad second-source coverage, reducing single-source risk on the BOM.