Fixed 3V rail, 300 mA — the dropout and PSRR matter
The MCP1802T-3002I/OT is a fixed 3V output LDO from Microchip, rated for 300 mA continuous. The 0.35V max dropout at 100 mA means a 3.3V input rail only needs 0.35V headroom to keep the output in regulation — a battery dropping to 3.35V still holds 3V clean. PSRR is 70 dB at 10 kHz, which knocks down switching regulator ripple by a factor of 3000 — useful when this LDO follows a buck converter to power an analog front-end or RF section.
Quiescent current and enable — always-on and shutdown
Quiescent current is 50 µA typical, so the regulator's own draw is negligible in battery-powered gear that stays awake most of the time. The Enable pin lets a microcontroller or switch pull the output to zero and drop Iq to near nothing in sleep mode. Over-current protection is built in — the part folds back without latching, so a temporary short on the output rail clears itself when the fault is removed.
SOT-23-5 package — rework and board fit
The SOT-23-5 (SC-74A) package is a standard small-outline transistor footprint. The five pins are on a 0.95 mm pitch — easy to probe, easy to hand-rework with a fine-tip iron or hot air. No exposed pad means no thermal vias to route, but the thermal resistance is higher than a DFN; keep the copper pour under the part for heat spreading.
ROHS3 compliant per the manufacturer.