This USB battery charging reference design is optimized for size in order to fit within an automobile power accessory port. The design features a USB dedicated charging port controller with integrated current limiting power switch and a 42V DC/DC converter. High integration and small package sizing allows a small form factor. Features Typical 13.6V input from car battery. Withstands 45V transients Accurate current limit (+/- 10%) Design provides up to 2.1A output current at 5V output Supports BC 1.2 Dedicated Charging Port specification Small 32mm x 16mm form factor Design has been built and tested.