A supplier of PSU's has designed one for us that has 14 layers of windings. Each layer is 2oz/70uM copper. The primary is 3 turns on each of the central
6 layers, all in parallel and the secondary is 1 turn on each of the 8 outer layers, again all in parallel. The mode is discontinuous flyback and the cores have a stepped gap between 2 E cores. This places the gap in the centre of the windings. This form of construction appears to go against at least one rule set by Unitrode. Have any designers out there got any thoughts about this?