If you want to build you own powerbank or just your own charger, this circuit is for you. It accepts input voltages of 6 - 15 V and outputs 5 V normally. However, if it detects a QC3.0 or FCP compatible device, it can adjust the output voltage continually up to 12 V (or Vin * 0.9, if you have lower Vin). Also, since it supports a ton of other protocols, it can charge most devices at max current.

Supported protocols:

• HiSilicon Fast Charging Protocol (FCP), ie Huawei phones (tested)
• Qualcomm Quick Charge 2.0/3.0 Class A: up to 12 V Output Voltage (tested)
• USB DCP (shorting D+ Line to D-) per USB Battery Charging Specification, Revision 1.2 (tested)
• USB DCP (applying 2.7V on D+ Line and 2.7V on D- Line), ie Apple 12 W
• USB DCP (applying 1.2V on D+ and D- Lines)
• Chinese Telecommunication Industrial Standard YD/T 1591-2009 (whatever that is, I have not tested that)

Specs:

• input voltage: 6 - 15 V, recommended 12 - 15 V
• input current: max 2 A
• output current: max 2 A
• efficiency (Vin = 12 V, Vout = 5 V, Iout = 1 A): 95 %
• efficiency (Vin = 12 V, Vout = 5 V, Iout = 2 A): 92 %
• quiescent current (no load connected, Vin = 12 V): 800 μA
• dimensions: see pictures; note that the board is hand-cut, so the outer dimensions might slightly vary

Notes:

• The source is in Eagle an is Open Source, so feel free to build it yourselves!
• It comes with a 2P screw terminal, please select if you want this already soldered or you want to solder it yourself.
• Protection: the switching regulator has a 2 A input current limiter and a short circuit protection. There are also two 1206 footprints, as of now populated with 0 ohm resistors. You could solder fuses there, but it is not necessary in my opinion.