Input source voltage supplied to the transformer is also supplied through {HEAD ~ a start up circuit} to drive the pulse width modulator and {TAIL ~ the main power switch} 
Input source voltage supplied to the transformer is also supplied through { HEAD ~ a start up circuit } to drive the pulse width modulator and { TAIL ~ the main power switch }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL