The MP5013E is a protection device designed to protect circuitry on the output (source) from transients on the input (VCC). It also protects the input from unwanted shorts and transients coming from the source.
A small capacitor on DV/DT controls the slew rate that limits the inrush current at the source. An internal circuit in DV/DT allows it to be floated (no connection) and still receive 1.2ms of ramp time at the source. The maximum load at the source is current-limited using sense FET topology. An external resistor between I-Limit and SOURCE controls the magnitude of the current limit.
An internal charge pump drives the gate of the power device, allowing the DMOS power FET to have a very low on resistance of only 36mΩ.
The MP5013E protects the source from the input being too low or too high. Under-voltage lockout (UVLO) ensures that the input remains above the minimum operating threshold before the power device turns on. If the input rises above the high output threshold, the MP5013E limits the source voltage.