I need to make an isolated DC-DC switching converter with a 9:1 output range and 5:1 input range. Power is about ten watt. Resulting 45:1 duty cycle range looks tricky to make work well.
So far I am most tempted to boost to an intermediate rail (which takes up the 5:1 range) and then convert from that over the 9:1 range. The intermediate rail could be useful for other purposes too.
However I came across descriptions of quadratic converters. Namely duty cycle variation needed would be SQRT(45), have any of you experience of those?