Lossless　passive　soft-switching　technologies　are　widely　used　because　of　their　simplicity　in　control　and　implementation.　A　novel　lossless　passive　soft-switching　cell　is　proposed　with　minimum　voltage　and　current　stresses,　which　is　suitable　for　all　basic　PWM　DC/DC　converters.　The　power　switch　turns　on　with　zero　current,　and　off　with　nearly　zero　voltage.　Meanwhile,　the　diode　switches　on　and　off　with　soft.　The　voltage　stress　of　the　switch　is　not　increased　compared　with　the　hard-switching　counterparts,　and　its　peak　current　is　limited　by　an　additional　inductor.　What＇s　more,　the　voltage　stress　of　the　diode　is　limited　with　the　help　of　clamping　diodes.　Soft　switching　is　realized　without　increase　of　voltage　and　current　stresses.　The　buck　converter　was　taken　as　an　example,　the　principles　of　the　novel　passive　soft-switching　cell　were　analyzed　in　detail　and　the　procedure　of　passive　parameters　design　was　deduced.　All　analysis　was　verified　by　simulation　and　on　a　100kHz,　200V/5A　buck　prototype.　Compared　with　the　hard　switching,　efficiency　was　tested　from　20%　to　rated　load,　the　proposed　soft-switching　scheme　had　a　distinct　better　performance.　©　2016　Chin.　Soc.　for　Elec.　Eng.