The LP3470IM5-2.83/NOPB comes in a SOT-23-5 package (SC-74A, SOT-753 equivalent), a 5-lead surface-mount footprint that fits standard 0.95 mm pitch layouts. The SOT-23-5 body is about 2.9 mm × 1.6 mm, so it consumes minimal board area and routes easily on a two-layer board with a single decoupling cap near the supply pin.
What the 2.83 V threshold means for your rail
The 2.83 V threshold is the voltage at which the reset output asserts when the monitored rail drops below that level. Open-drain lets you wire-OR multiple reset signals to a shared pull-up resistor on the microcontroller's reset line.