Active production — still a current BOM line
The LT3055MPMSE-5#PBF: This is a current-production part, not a discontinued or NRND line that would force a board spin.
5 V fixed rail at 500 mA — what the ratings mean for fit
This is a single-output positive LDO regulator with a fixed 5 V output and a 500 mA current rating. The 45 V maximum input gives wide headroom for unregulated supplies or 24 V industrial rails — a common bus in factory automation panels. Dropout voltage is 0.59 V max at the full 500 mA load, so the input rail must stay above 5.59 V to maintain regulation. Below that threshold the output follows the input minus dropout — the part does not fold back gracefully, so budget the headroom. Quiescent current is 130 µA typical, which keeps the part viable for always-on or battery-backed rails where the regulator's own draw matters for standby power budgets.
The 66 dB power-supply rejection ratio at 120 Hz directly addresses the dominant ripple frequency from a full-wave rectified mains supply. That is roughly 2000:1 attenuation — a 1 V pk-pk ripple on the input becomes about 0.5 mV at the output. For sensitive analog front-ends or ADC reference rails this keeps the supply noise below the converter's LSB.
The operating junction temperature range spans -55°C to 150°C, which is the military-grade band. The 150°C absolute maximum junction means the thermal design must keep Tj below that under full load and worst-case ambient.
16-MSOP-EP — package and thermal pad
The part comes in a 16-lead TFSOP with an exposed pad (3.00 mm width), also referred to as 16-MSOP-EP. The tube packaging means it ships in a stick, not tape-and-reel, so pick-and-place feeders need a tube adapter or a tray conversion.
Control and protection features
On-chip control features include current limit, enable, power good output, and soft start. The protection suite covers over-current, over-temperature, and reverse polarity — the reverse-polarity clamp is useful for systems where the input connector can be miswired, as it prevents damage without an external series diode that would add dropout voltage.