5 V fixed LDO, 1 A — dropout and thermal budget
The LM2940IMPX-5.0 is a fixed 5 V positive-output LDO from Texas Instruments, delivering up to 1 A continuous output with a maximum dropout voltage of 1 V at full load. That 1 V headroom means the input rail must stay above 6 V under worst-case line and load transients to maintain regulation — a common constraint when deriving a clean 5 V rail from a 7 V to 26 V input bus in industrial or automotive auxiliary supplies. The part integrates over-current, over-temperature, reverse-polarity, and short-circuit protection, so it can sit on a board without a separate crowbar or foldback circuit for the output.
The SOT-223-4 package is the standard surface-mount footprint for this 1 A LDO family.
PSRR at 120 Hz — a spec that matters for post-rectifier rails
The power supply rejection ratio is 64 dB at 120 Hz.