LTC3786 single cell battery booster up to 20 V 5A
The PCB and schematic is designed by EasyEDA which you can find it here https://easyeda.com/
Also the project page on EasyEDA is here https://easyeda.com/hamedta/ltc3786
it uses LTC1754 to boost up battery voltage to 5v to supply the bias voltage of LTC3786 so as to be able to work with battery voltage down to 2.5 V