Patent ID: 7102898

Claim:
A switch-mode power converter for converting an input voltage from an input source to an output voltage for supply to a load, the power converter comprising: a power isolation transformer having a primary winding and split first and second secondary windings; a primary converter circuit connected to said primary winding of said power transformer, said primary converter circuit comprising at least a first and a second primary controllable power switch each said switch having two control terminals for alternatively supplying the input voltage to said primary winding of said power isolation transformer to produce a substantially symmetric current in said primary winding; a full wave secondary converter circuit fully isolated from said primary converter circuit and comprising first and a second synchronous rectifiers, said synchronous rectifiers being individually switchable and each being connected between a respective one of said first and second secondary windings and the load; at least a first and a second primary switch control circuit controlling the conduction of said first and second primary controllable power switches; synchronous rectifier control circuits controlling conduction of said each first and second synchronous rectifiers; a switch conduction control circuit with two outputs having substantially symmetrical waveforms shifted by about 180 degrees for controlling the conduction of said primary controllable power switches and said first and second synchronous rectifiers; and a drive transformer used for providing necessary delays between conductions of said primary controllable power switches and said first and second synchronous rectifiers as well as providing power for controlling said primary controllable power switches and said first and second synchronous rectifiers, said drive transformer providing isolation between said primary switch control circuits and said synchronous rectifier control circuits, and said drive transformer comprising: a first drive transformer winding connected to said switch conduction control circuit; and a second drive transformer winding connected to said first primary switch control circuit, said second drive transformer winding controlling the conduction of said first primary controllable power switch.