The STMicroelectronics ST732M28R is a fixed-output low-dropout voltage regulator delivering 2.8V at up to 300mA from an input rail that can go as high as 28V. That input range is the headline differentiator — most LDOs in a SOT-23-5 package top out around 5.5V or 16V, so this part suits designs where the raw supply is a 24V industrial bus, an automotive battery line, or a multi-cell Li-ion stack that needs a clean 2.8V rail for a sensor or MCU.
Dropout and headroom — the 1.2V max at full load
Maximum dropout is specified at 1.2V when delivering 300mA. That means the input needs to stay above 4.0V (2.8V + 1.2V) to maintain regulation at full current. If your rail is a 3.3V bus with margin, this part isn't the fit — look for a lower-dropout device. But if you're dropping from a 5V, 12V, or 24V rail, the headroom is generous and the dropout spec won't be the constraint. The 200 µA maximum supply current is worth noting for standby-power budgeting.
Protection and package — no external watchdog needed
Over-current and over-temperature protection are integrated, so a short on the output or a thermal runaway condition shuts the regulator down without an external supervisor. The SOT-23-5 (SC-74A) footprint is standard and rework-friendly — no exposed pad to solder, just five pins.
For the storeroom, store the reels dry — SOT-23-5 is MSL 1 by default, but always check the bag label.