SY8113B

The SY8113B is a high efficiency 500 kHz synchronous step-down DC-DC converter capable of delivering 3A current. Some NanoPi and Orange Pi boards use it for powering their boards. The chip does not support I2C or any higher level protocol for communicating the voltage parameters so the boards use a simple GPIO driven resistor array to switch between two voltages (1.1V and 1.3V).

Datasheet: http://www.datasheetspdf.com/datasheet/SY8113B.html