Looks like it might be an MP65151DJ from Monolithic Power Systems. For reference from the datasheet ([pdf][1]):

[![enter image description here][2]][2]


Note the TSOT23-6 chip marking of AAN for an active-high chip (pretty sure the vertical line in your picture is the pin 1/polarity indicator). The circuit on your board seems to match the pinout as well (pin 2 = GND, pin 5 is a resistor to GND, pin 6 looks like an output with some output capacitance, etc.)


  [1]: https://www.mouser.com/datasheet/2/277/MPS07272018_MP65150-1382652.pdf
  [2]: https://i.sstatic.net/Zx9hj.png