5V fixed rail for noise-sensitive loads
The LM2931ADT50R is a 5V fixed-output LDO from STMicroelectronics, delivering 100 mA continuous current with a maximum dropout of 0.6 V at full load. A single regulator in a positive output configuration, it includes current limit and thermal shutdown protection — no external enable pin, so the output is live whenever Vin is present.
Dropout and headroom budget
With a 0.6 V maximum dropout at 100 mA, the input must stay above 5.6 V to maintain regulation. The 26 V absolute maximum input gives plenty of margin for 12 V or 24 V industrial rails, but the quiescent current of 1 mA is worth noting for always-on battery applications — every microamp counts when the coin cell has to last.