Customer Reviews

Demystifying Switching Power Supplies (The Demystifying Technology Series)

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In general I bought this book hoping for explanations of the basics of SMPS converters but I have been greatly disappointed. I had to refer to other works, just to understand some simple terms.

Some concrete examples:-

1. Introduction page xii: in the example given, if each battery voltage cell is 1.9V when discharged and there are 5 such cells, the minimum supply voltage is 5 x 1.9V = 9.5V (not 9.9V as stated in the book). A small mistake but this changes all the remaining calculations. E.g. the regulator dissipates 7W (not 7.8W) and the efficiency is 63% (not 60%) when the battery is fully discharged.

2. Page-4: just poor editing, the 10 Ohm load in the calculation does not correspond to the 100 Ohm load as marked in Fig 1.1

3. Page-4: it is not clear why the Buck circuit is so named just because the "inductor opposes the supply voltage"...in fact in any circuit where there is an inductor and a voltage source, the inductor will always 'oppose' the voltage source (or am I wrong?), so can this be the reason to call this circuit a Buck converter?

4. Page-4: A basic term such as 'Duty Cycle' is not defined at its point of first use. In fact Duty Cycle is not defined anywhere in this book (as far as I can see). 'Duty Cycle' does not even appear in the Index (and there is no Glossary of Terms). It should be stated somewhere (pref. on page-4) that Duty Cycle = Ton / T.

5. Page-4: Eq 1-6 is essential to understanding how SMPS work but is not explained (and this does not require much Maths).

6. Page-11: The author states "it appears that this supply uses a transformer, but in fact, the magnetic component is an inductor with two windings". Maybe my poor understanding but where is the difference? Is it because the two windings are out of phase? When are two coupled inductors not considered a transformer? From the book, it is not clear. If someone can explain this to me, I would really appreciate the explanation...

There are many more examples of poor explanations in this book but at this point I give up...

If you really want to understand SMPS, do not waste your good money (in my case GBP 46.50) on this book, instead, simply download the following free resources:

a. All About Circuits Volume 2 on AC Circuits (Google it)
The single best explanation of any and all aspects of electric circuits I have ever read in my life (and its free...!!)

Also highly recommended:
b. ON Semi Switchmode power supplies Ref Manual
c. National Semi Application Note AN556

Hope I saved you guys some money...

If you desire to know how various switching regulators work, this is the book to get.
The switching regulator is really the heart of a switching mode power supply.
The writing is very clear and along with the diagrams easy to understand.

I have owned this book for some time and i keep going back to it for Reference. This book discribes in detail offline and DC DC SMPS supplys. It is missing a cuple more advanced techniques and methods, But it covers everything most pepole in this feald will need to know or run in to. This is a must have in this day and age for anyone in the electronics industry.