A high efficiency USB power management system that safely charges Li-Ion/Polymer batteries from automotive supplies is described.
LT3480 high voltage step-down regulator
LTC4098 Li-Ion/Polymer battery charger
Automotive power systems are unforgiving electronic environments. Transients to 90V can occur when the nominal voltage range is 10V to 15V (ISO7637), along with battery reversal in some cases. It is fairly straightforward to build automotive electronics around this system, but increasingly end-users want to operate portable electronics, such as GPS systems ...