off-the-shelf SMPS transformer - Page 1
Forum section: electronics / projects

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 13, 2014, 08:25:50 am
content: Well this is my second post about those SMPS transformer, and since the first one didn't get much of answer i think i was asking the question the wrong way, so i think i will asked like thisWhat make the SMPS transformer really unavailable "off-the-shelf" it's a real pain in the ass to find a suitable one?Most of manufacturers have sampling ... but it take ages to get the sample and of curse you have to fill 100 text box in form for what you need this sample for , who are you, what estimated production when production start... so for small custom design no chance to get onedamn it

author: janengelbrecht
author_rank: Regular Contributor
timestamp: November 13, 2014, 08:28:47 am
content: Make one yourself then ?Well I only wanted to say that the reason for no answers could be that you havent made a question....only observations

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 13, 2014, 09:05:42 am
content: hhh you killing me" What make the SMPS transformer really unavailable "off-the-shelf" "that's the question , the rest of it me angryin another word what seems to be the reason for this particular component not to be present in distributor's stock like Farnell or mouser, with different power ratting and output even for typical applications ...Even if i check manufacturer catalogue such as Wurth , only some small power transformer are available. Hope i have a question to debate about it now

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 13, 2014, 12:44:36 pm
content: There are some standard parts. Hundreds in fact. But if none of them are quite right in your application, that's where your problem happens.There are already four parameters to specify, just to even begin selecting a transformer: input voltage, power level, output voltage (secondary), and auxiliary (if any). And supply voltages might pick between 3.3V and 480V, power levels from 1W to hundreds, output 3.3V to 48V or more, and auxiliary 5 to 20V at low current. Thousands of possibilities, and that's not even including frequency range, aspect ratio (physical size and shape, tall and thin or short and wide?), topology (flyback, forward, resonant?), additional secondaries (multiply the choices by hundreds!) and more (snubber winding, esoteric things like saturable windings, etc.).Tim

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 13, 2014, 01:19:20 pm
content: Because of their considerably incrased complexity, SMPS tend to be custom-designed for applications where the economies of mass-production make custom-designs the standard procedure.OTOH, a search for "smps transformer" on DigiKey returns 900 hits, 555 of which are in-stock, so it is not clear exactly what you are asking?

author: DanielS
author_rank: Frequent Contributor
timestamp: November 13, 2014, 01:55:30 pm
content: Long story short: off-the-shelf SMPS transformers are rare because there are too many variables in SMPS designs so most non-trivial applications end up requiring custom transformers.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 13, 2014, 02:14:22 pm
content: Quoteyap that's exactly what am referring to, 50/60Hz transformer tend to be more available. even if all recent design using more than 15W or so use SM transformer.Quote from: Richard Crowley on November 13, 2014, 01:19:20 pmfrom those 555 in stock i found one almost fit what i needI was looking for flyback transformer 85-265 input 15V 6A outputAny way what am asking for is the raison why such component tend to be custom designed and as you explained a lot of specification change from an application to an other so will be difficult to cover all of them, however it will be good to have a fixed model for most used voltage like 12 24 48 with some power step for 10 to 150 step of 10W for example. that will make life easier for lot of ppl.

author: wraper
author_rank: Unknown
timestamp: November 13, 2014, 03:13:59 pm
content: I came to conclusion that if you need something trivial, it is cheaper/easier to buy off the shelf psu, like MeanWell for example. If you do need something more specific, then you would need custom transformer anyway.

author: German_EE
author_rank: Super Contributor
timestamp: November 13, 2014, 03:41:11 pm
content: This is because Coilcraft work with the semiconductor manufacturers, they specify Coilcraft products in their application notes and Coilcraft list a part as "suitable for Xxxx". The relationship works well.

author: Marco
author_rank: Super Contributor
timestamp: November 13, 2014, 03:50:59 pm
content: Quote from: hamdi.tn on November 13, 2014, 02:14:22 pmSearching for 90W flyback transformer gave me the Myrra 74060 as the second result (searching for some nice round wattage numbers near your requirements and having patience while manually combing through the results is probably the best search strategy for switching transformers). Availableat Farnell for ~11 Euro. A bit overspecced at 10A total, but if you want to be on the dot you get something custom made.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 13, 2014, 11:40:52 pm
content: Note also that anything from 12 to 24V (secondary) will likely work, as flyback designs are generally very tolerant of crappy ratios. Adjust frequency and on-time to suit.Tim