Here’s an application note from Maxim: Enable automotive USB power – Managing the increasing currents, longer cables, and tight portable-device specifications
This application note discusses the challenges of rapid USB charging of today’s portable devices (PDs) in an automobile. The PDs may not charge quickly or charge at all, especially the more recent power-hungry devices. We explain why low-cost USB car chargers are not the solution because they introduce radio interference (RF) into the vehicle. We discuss a new DC-DC converter with a smart USB switch that leverages tight integration to provide automotive-specific USB power, USB charge enumeration, and port protection. It solves recent problems with higher PD charging current.
A similar version of this article appeared in the July 21, 2013 issue of Electronic Products