Description

This reference design is a 12-V pre regulator reference design for multiple automotive applications powering up to 36-W. The used SEPIC topology allows to step up and step down the input voltage: so cranking down to 5-V is supported; the controller LM5122 itself allows cranking down to 3-V at reduced power level.  Due to continuous currents at the input of any SEPIC topology the reflected ripple is low: means conducted emissions are reduced just by using smart topology. For even lower EMI the design is able to operate in forced PWM mode: for best light load efficiency a true diode emulation could be selected via jumper.  Synchronous rectification results in full load efficiency 93% + and fine thermal behavior - by using a generic dual inductor from stock.