Fixed 3.3 V rail for noise-sensitive loads
The LD1117AV33 is a fixed 3.3 V output LDO from STMicroelectronics, rated for 1 A continuous output. The 1.3 V maximum dropout at 1 A means the input rail must stay above 4.6 V to maintain regulation at full load. If the input sags below that, the output follows — sequence the rails with enough headroom.
Dropout and quiescent budget for the BOM
At 1 A output, the quiescent current is 10 mA. That 10 mA is drawn from the input regardless of load — it is not negligible in battery-powered designs but is typical for a 1 A LDO of this generation. The thermal budget in the TO-220 package at 1 A with 1.3 V dropout dissipates 1.3 W; a heatsink is required for ambient temperatures above 50°C unless the load is intermittent. Protection features include over-current and over-temperature shutdown, which latch off the output until the fault clears.
Active production — ordering and lifecycle
Production orders can be placed without LTB planning. The part is ROHS3 compliant.