# Switching power supply beginner

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#### yut

##### Newbie level 3
beginner power supply design

How can I start design the switching power supply?
What is the knowledge that I must to know?
Thanks for your answer.

### yut

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#### VVV

##### Advanced Member level 5
Try this link: www.smps.com
There is also a good book out there, A.I. Pressmann's "Switch-mode power supply design".

### yut

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#### vicky

##### Full Member level 4
hi
dar i think that firts off all yu need to know about the basics of the smps .

### yut

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#### v_c

##### Advanced Member level 2
Is there anything in particular that you want information on? For example, if you need to design a 12V to 5V switching converter, you would probably use a Buck converter. And there are lots of application notes from power IC manufacturers that target this area. These notes are not the datasheets, but provide a more general theoretical look at switchmode topology of interest. The reason I am mentioning this is because, as a beginner, you could spend months on learning the different circuits and still not have anything useful for your needs. So if you can give more specifics, I think more relevant information will be out there.

Besides the book by Pressman, another good book is "Switchmode Power Supply Handbook" which is available on EDAboard

Just try Google and you will find lots of information. These site have already been mentioned are pretty good -- the relevant sections for you might be the tutorials

https://www.smpstech.com/tutorial/t00con.htm
https://www.smps.us/smpsdesign.html (left column)

Best regards,
v_c

### yut

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#### ARTMehr

##### Full Member level 2
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### yut

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#### E-design

##### Advanced Member level 5
I started about 20 years ago by looking at application notes from Unitrode, SGS (now STI), Motorola, Philips etc. after studying the basic topologies and equations that governs them. One point of good advice I can give you: Don't neglect the magnetics construction or you will be disappointed! Take great care if you have to construct any ferrite choke or transformer, and pay attention to winding layout, layers stacking, insulation etc. At higher frequencies > 100kHz leakage inductance becomes a real problem and will come back to bite you in the form of voltage spikes and blown devices. Start with low power designs and work your way up to the big stuff. This way you will build up confidence and learn from your mistakes (may be very costly at high powers) blowing up a 150A, 500V IGBT device on a 37kW switcher (happened to me years ago) does not make the boss very happy! You will learn how to take precautions at high power (de-saturation detection, current slope trips..) as you get more experience. Also from Murphy's "The transistor will blow to protect the fuse" is very true. As one of my friends used to say: "Remember the fuse is only there to prevent the whole damn building from burning down"

### yut

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#### v_c

##### Advanced Member level 2
I have destroyed few MOSFETs, but not too many
Some people refer to destroying devices as "letting the smoke out". And once the magic smoke is out of the device it will not function anymore.

I agree with you 100% regarding magnetics, unfortunately, it is not taught at many schools these days and when it is taught it tends to be theoretical rather than practical.

A good online resource for magnetics is the "2001 Magnetics Design Handbook" from a Texas Instruments seminar. It is archived here

https://focus.ti.com/docs/training/catalog/events/event.jhtml?sku=SEM401014

Here are the basic topics.
Code:
Introduction and Basic Magnetics (Magnetics Design for Sw. Power Supplies)
Magnetic Core Characteristics
Windings
Power Transformer Design
Inductor and Flyback Transformer Design
Ref. Design Sect. R1-1: Magnetic Core Properties
Ref. Design Sect. R2-1: Eddy Current Losses in X-former Windings
Ref. Design Sect. R3-1: Deriving the Equivalent Electrical Circuit
Ref. Design Sect. R4-1: The Effect of Leakage Inductance on Performance
Ref. Design Sect. R5-1: Coupled Filter Inductors Yield Improved Performance
Ref. Design Sect. R6-1: How to Design a Transformer with Fractional Turns
Ref. Design Sect. R7-1: Winding Data

### yut

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#### E-design

##### Advanced Member level 5
It is a shame that they don't teach practical magnetics. This is what makes or breaks the design. I wonder if students know about baker clamps and other tricks, seeing that everything is power fet these days? From what I am told universities are concentrating more on the resonant stuff ZVS, ZCS today as the drive is for smaller and more power. But again very little practical HF transformer construction from what a PhD student told me. Everything is done on simulators, which assume perfect or near perfect magnetics. This student was quite surprised to see how the waveforms actually looked on a scope under real operating conditions. Welcome to the real world!

### yut

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