Hi MrAl,
Switch mode power supplies are a devil to understand, and there does not seem to be one book that covers the basics thru to a high level. Often the best way to grasp a difficult subject is to read about it described from different angles and pick out the bits that gel- the scatter gun approach.
I hope all the data does not overwhelm the OP who does not seem to have had much luck with the same question on other sites.
One of the problems is that there does not seem to be one book that goes from the basics of switch mode power supplies thru to a high level, so it seemed best to let the OP do what I do in such cases and mix and match from various sources.
spec