For Automotive Front lighting is a stable input voltage for switched mode current regulator an important tool. First the battery voltage has to be stabilized with a Buck Boost to provide to next multiple Buck converter stages a stable input voltage. Depends on led-string solutions the total current defines the power level of various buck stages. The main buck-boost has to have the total power level for complete lighting control unit. The efficiency of buck-converters depend on synchronous or non-synchronous topology. For the light engine is also a feedback loop for led-string current control quite important.