Recommended reading/watching for SMPS PSU design - Page 1
Forum section: electronics / beginners

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 25, 2015, 02:29:08 am
content: I've been reading and watching lot of videos on power supplies, mostly SMPS as that is what interests me more due to better efficiency, but I still have a few questions. Open to recommended watching/reading as well. Most of my research has just been random videos I've found while searching youtube and what not.I understand the general concept, mostly the boost converter part, but still have a few questions, I may as well ask them here, but feel free to just redirect me to some reading I can do which will answer them:1: How do you properly size the transformer? Looking at Digikey for fun at SMPS transformers the actual values seem very low, like a few watts. I'm guessing these are based at a fixed frequency like 60hz and those numbers go up depending on the frequency you run it at?2: Other than the transformer what else determines the actual capacity? I'm guessing the mosfet? Also how does it work when there are multiple mosfets, how do you make them balance the load?3: How do you power the microprocessor or other components that handles the PWM? Ex: if they take 5v how do you produce that 5v initially? Guessing you'd use some kind of linear regulator then have relays that switch to the SMPS's output power once the SMPS is "started up"?4: Lastly, is there a reason using a SMPS would be bad for a bench supply? I'd like to build my own more or less from scratch once I know more. Mostly for a challenge. I know they can be a bit noisy but is that really an issue? I can always use it to drive a small linear IC for whatever I'm working on if noise is an issue.Thanks in advance.

author: Cliff Matthews
author_rank: Unknown
timestamp: March 25, 2015, 02:48:35 am
content: Chip makers provide lots - granted the ideas feature their products, but it's a good start.http://www.onsemi.com/pub/Collateral/SMPSRM-D.PDF

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 25, 2015, 11:10:27 pm
content: Thanks, found and read through that actually. Open to other reading suggestions too.

author: kezat
author_rank: Contributor
timestamp: March 25, 2015, 11:38:19 pm
content: "The Post Apocalyptic Inventor" has a video series on the subject, I don't think he has completed it yet but some good info in what he has done.

author: Sirius631
author_rank: Contributor
timestamp: March 26, 2015, 04:24:20 am
content: Quote from: kezat on March 25, 2015, 11:38:19 pmYes, I wish he'd get back to that and finish it off.

author: Rog520
author_rank: Regular Contributor
timestamp: March 26, 2015, 04:55:57 am
content: Sanjaya Maniktala's books are hands-down the best on SMPS design, especially for non-isolated topologies. Check out his "Switching Power Supplies A-Z." For the nitty-gritty on transformer-based supplies (forward, bridge, etc.), Abraham Pressman's "Switching Power Supply Design" is the classic, and has been recently revised.Transformer design is almost as much art as science, and the particular procedure will depend on a lot of factors. Most off-the-shelf transformers are generally capable of lower power. Source like Magnetics, Inc. can supply you with a lot of information of cores and design help based your desired capacity, operating frequency, etc. Micrometals is a good source for lower-cost powdered-iron cores if you're designing things like chokes or inductors. All of the core manufacturers have a wealth of info to get you started, and the above-mentioned books also will be very helpful.Usually you'll choose a topology based on what kind of capacity you'd like to achieve. For transformer-based designs, lower power to higher power goes roughly in the order of flyback, forward, push-pull, half bridge, full bridge. More advanced higher power designs rely on resonant switching to mitigate switching losses and EMI.You can use a separate auxiliary ("housekeeping") supply to power the micro and supporting circuitry, or you can bootstrap the auxiliary supply from the output of the SMPS.I would personally choose a linear supply for bench work, especially if you're making your own. Unless it's carefully designed, noise from a switching supply can cause all sorts of headaches.

author: ketil b
author_rank: Regular Contributor
timestamp: March 26, 2015, 06:30:09 am
content: HiI am currently readingSwitching Power Supplies A - Z, Second Editionand i would highly recommend it, it is ezey to read and understand.

author: DutchGert
author_rank: Frequent Contributor
timestamp: March 26, 2015, 10:26:39 am
content: I totally agree with the above two comments.http://www.amazon.com/Switching-Power-Supplies-Z-Second/dp/0123865336is one of the best and most comprehensive books on the topic.

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 27, 2015, 01:43:13 am
content: Thanks I'll definitely have to check out that book.

author: rbola35618
author_rank: Frequent Contributor
timestamp: March 27, 2015, 04:35:13 pm
content: I have a number videos on flyback design as well as two switch forward converter. It is a work in progress as I get time.These videos were intended as training material for our junior engineers at my place of employment. I show how to analyze the converter, derive equations using the volt-second rule and then show how to simulate the converter using TopSPICE. The SPICE file are available on request at rbola35618@aol.comJust want to add that I am passing what me Jack Alexander, who was a world class power supply designer, taught me. Jack Alexander designed over 130 power supplies flying in space. The last power supply that he designed is presently flying to the planet Pluto in the New Horizon Spacecraft.Hope you find the videos usefull.Robert Bolanoshttps://www.youtube.com/user/rbola35618

author: Red Squirrel
author_rank: Super Contributor
timestamp: April 02, 2015, 07:54:21 am
content: I'm having trouble justifying the price of books when I much prefer something on the computer, is there a reliable place to get PDFs of books for cheaper? I don't want to pirate it nor get it from a sketchy source, but I'm wondering if there are author supported sites that perhaps provide PDF downloads of books for a cost but cheaper than in print.I might also just dive in with the little bit of knowledge I've gotten from various online sources and see how far I get into it before I decide to get into it seriously. Might very well end up just going the linear route for my first bench supply, I can always build a SMPS one later on too, never hurts to have multiple anyway. In fact I'm thinking of building a small very low current one using LM regulators just to get me by. Probably getting too much ahead of myself jumping straight into SMPS, but I tend to like giving myself a challenge.

author: Sirius631
author_rank: Contributor
timestamp: April 03, 2015, 02:56:20 am
content: Check out Afrotechmods on YouTube. He does a cool tutorial series on SMPS. I think I'll be plugging my first ever Arduino based SMPS buck converter solar panel charge controller together over this weekend, after following the series.