Fixed 3.3 V rail for noise-sensitive loads
The MCP1791-3302E/ET: Its 30 V maximum input voltage lets it run directly off unregulated 24 V industrial supplies or 12 V automotive buses without a pre-regulator. Power supply rejection ratio of 90 dB at 100 Hz to 80 dB at 1 kHz means this part attenuates ripple from switching converters or rectified mains by a factor of 10,000 to 100,000 — relevant for powering analog front-ends, sensor bridges, or reference buffers where supply noise couples into the signal path.
Thermal and control features for industrial bias rails
Operating temperature spans -40 to 125 °C, covering the full industrial and automotive under-hood range. The 5-lead DDPAK (TO-263-6 variant) package includes a tab for heat sinking; with 70 mA output and a 1.3 V max dropout at full load, the worst-case dissipation is under 100 mW, so the tab can be tied to a ground plane without forced airflow. Enable and Power Good pins simplify power sequencing — the Enable pin can hold the output off until the upstream rail is stable, and the Power Good open-drain flag signals when the output reaches regulation. Quiescent current is 130 µA typical, rising to 210 µA maximum, making this LDO suitable for always-on bias rails in battery-backed or energy-harvesting systems. Built-in over-temperature and short-circuit protection allow the part to survive output faults without external crowbar or foldback circuitry — the thermal shutdown cycles the output until the fault clears.