A step-up (also referred as boost) circuit is used to generate a higher voltage than the input voltage. The polarities are same as in the input. Output current is about 2-4A while ECE is about 80%.

Can be easily modified to produce 19V output for laptops (even on the fly using switch and resistor) in car.

PCB was made firstly for the manual manufacturing so tracks widths are not meaningful and serve illustrative purposes. Remember that important critical parameters are closely related to conductors sizes.

Free space at the bottom is left for heat sinks as MOSFET and Schottky diodes are the most heated components.