Design AC-DC power supply using Innoswitch and custom transformer

[VEGETA]

Hello,

I have designed and sold this product: https://thundertronics.net/product/dreamcast-universal-power-supply/

I am currently making a batch of 40 which are expected to be sold fast too... However, I am using a very good and expensive power module from Recom.

PCB manufacturer gets it for me for about 23-24$ in quantities from suppliers like Digikey and Element14-CN. I got quotes from manufacturer themselves for 12.1$ per unit in quantities but I have to set shipping carrier account...etc. Overall still very expensive component.

I wanted to go to next level and design my own flyback regulator... it outputs 12v or 15v then I hook whatever buck regulators after it as I need.

I contacted Power Integration and they suggested Innoswitch3 IC and gave me example design with everything detailed. they said the transformer can be made from magnetics makers for 7$.

I contacted Prem magnetics and they are looking into this suggested transformer design... if price is ok i will modify the design to my liking which won't be much different.

I cannot wind my transformer myself for many reasons, I have to get it ready and delivered to pcb manufacturer.


Kindly inform me about your experience doing this + the cost of this circuit especially the custom transformer. Is it realistic that I hope the transformer be in 2-5$ range? what other good manufacturers (in China for example, but still good) that can make it cheaper?

please give me full recommendation and your experience doing this.

P.S: this product is for Dreamcast and it is 30W (DC is just 22W), I am doing a Saturn version which is <15W and could do more versions for other devices and stuff. Current design has noise and ripple value of <25mv p-p (a third party friend confirmed 15mv) and it is ice-cold. Only downside is BOM cost and availability.

I attached the Innoswitch3-CE suggested design for 15v 2A max output + all transformer details.

[moffy]

The transformer size will be dependent on switching frequency, primary inductance and power rating. The circuit from Innoswitch3 looks good and quite efficient with a synchronous rectifier on the secondary side, handling the regulation and isolation in one chip is an added bonus. Custom transformers can be quite cost effective when ordering in bulk, just be sure to choose a magnetic core that has good availability, like ICs not all cores are equally available and you would like your transformer design/pcb layout to last the test of time.
Just one problem, certification, devices connected to the mains need to be certified and pass qualification testing. This is probably one extra thing your purchased PSU did for you.

[VEGETA]

The transformer size will be dependent on switching frequency, primary inductance and power rating. The circuit from Innoswitch3 looks good and quite efficient with a synchronous rectifier on the secondary side, handling the regulation and isolation in one chip is an added bonus. Custom transformers can be quite cost effective when ordering in bulk, just be sure to choose a magnetic core that has good availability, like ICs not all cores are equally available and you would like your transformer design/pcb layout to last the test of time.
Just one problem, certification, devices connected to the mains need to be certified and pass qualification testing. This is probably one extra thing your purchased PSU did for you.

what cores do you suggest I use?

as for certifications, i won't need them since i sell direct or via some niche suppliers in retro gaming industry. won't need any certifications as also i never needed them when i sold my current design itself.

how much does the transformer cost in your opinion? approx.?

[xvr]

> PCB manufacturer gets it for me for about 23-24$ in quantities from suppliers like Digikey and Element14-CN. I got quotes from manufacturer themselves for 12.1$ per unit

https://www.lcsc.com/product-detail/Power-Modules_HI-LINK-HLK-30M12C_C18203068.html - $5.45
https://www.lcsc.com/product-detail/Power-Modules_HI-LINK-HLK-30M12_C2761166.html - $10.49
https://www.lcsc.com/product-detail/Power-Modules_TDPOWER-TAS30-12-W_C570985.html - $8.1

Take a look also at Meanwell and Chinfa models.

Recom is a quite expensive manufacture.

[VEGETA]

> PCB manufacturer gets it for me for about 23-24$ in quantities from suppliers like Digikey and Element14-CN. I got quotes from manufacturer themselves for 12.1$ per unit

https://www.lcsc.com/product-detail/Power-Modules_HI-LINK-HLK-30M12C_C18203068.html - $5.45
https://www.lcsc.com/product-detail/Power-Modules_HI-LINK-HLK-30M12_C2761166.html - $10.49
https://www.lcsc.com/product-detail/Power-Modules_TDPOWER-TAS30-12-W_C570985.html - $8.1

Take a look also at Meanwell and Chinfa models.

Recom is a quite expensive manufacture.

yes i know recom is expensive but very high quality and safe (medical rated). chinese units are not guaranteed to be safe and reliable as you well know. i marketed the device as a safe PSU, since you can find other solutions for that market which are not safe enough. this one was labelled a premium product by customers which it is for sure.

I know recom is expensive but it fits my pcb tight space and  so on... it also has all components inside like input protection unlike most others.

[moffy]

as for certifications, i won't need them since i sell direct or via some niche suppliers in retro gaming industry. won't need any certifications as also i never needed them when i sold my current design itself.

"yes i know recom is expensive but very high quality and safe (medical rated). chinese units are not guaranteed to be safe and reliable as you well know. i marketed the device as a safe PSU, since you can find other solutions for that market which are not safe enough. this one was labelled a premium product by customers which it is for sure.

I know recom is expensive but it fits my pcb tight space and  so on... it also has all components inside like input protection unlike most others."

You realise that there is a contradiction in these two statements? You buy the Recom because it is medically rated and very safe, but you don't need to certify a supply you build yourself? Also Meanwell are very decent PSUs, it takes experience to make good PSUs.

[VEGETA]

as for certifications, i won't need them since i sell direct or via some niche suppliers in retro gaming industry. won't need any certifications as also i never needed them when i sold my current design itself.

"yes i know recom is expensive but very high quality and safe (medical rated). chinese units are not guaranteed to be safe and reliable as you well know. i marketed the device as a safe PSU, since you can find other solutions for that market which are not safe enough. this one was labelled a premium product by customers which it is for sure.

I know recom is expensive but it fits my pcb tight space and  so on... it also has all components inside like input protection unlike most others."

You realise that there is a contradiction in these two statements? You buy the Recom because it is medically rated and very safe, but you don't need to certify a supply you build yourself? Also Meanwell are very decent PSUs, it takes experience to make good PSUs.

I mentioned the high ratings of recom in product description, and will be mentioned in product video when it is done. it is just that i don't want to do any official certification for my product.

yes meanwell are nice, it was my first choice but the space is so tight and it didn't fit. recom one is shorter... the 12v 30w ones anyway.

the topic of this discussion is about flyback converter and custom transformer design, not power modules. i did ask about power modules here before and got similar recommendations to use recom or meanwell.

overall, getting a custom transformer with innoswitch could be cheaper in the long run but i wanted to ask if someone went this route to help me by giving details about custom transformer price and reliability of this solution. since all these power modules are just that, a flyback converter with input + output filtering and protection.

[xvr]

Custom flyback is a not simple thing to develop. First of all there is not a transformer in flyback but a multiwind inductor. They have different construction and can't be interchangebly used. Flyback inductor has a air gup in core, and this gap is essential.
Next - China supplier will not produce custom goods, they specialise on mass product, and flyback inductor is not a 'mass product'
On the other hand, even custom China based inductor still be Chinese product, and reliability of whole power supply will be compromized by this inductor. So why you think that ready made Chinese module will be less reliable?
It you want to find something ready nade you should take a look at Coilcraft for example.
As for custom designed flyback - I'd made one mamy time ago . It was based on TOP2 family from PowerIntegration and custom transformer (made on EPCOS ferrite). It works fine 24/7, and finally blown up after 5-8 years of service.

[jonpaul]

40...few 100 pcs not worther the NRE, MPQ to DIY the SMPS.

Get a cheaper off the shelf module, from China if you like to.

suggest you learn a bit....find and  Read a few SMPS texts on design and magnetics, safety and compliance.

j

[NiHaoMike]

How about just have a DC input and include a wall wart with the product?

[VEGETA]

Custom flyback is a not simple thing to develop.

everything is done by power.com tools. if i settle on a certain design then i will get a sample transformer from them since they have such a service. after that i can check to see who can make them for me. right now i am waiting prem magnetics to respond.

i want to use innoswitch3 ic

40...few 100 pcs not worther the NRE, MPQ to DIY the SMPS.

Get a cheaper off the shelf module, from China if you like to.

suggest you learn a bit....find and  Read a few SMPS texts on design and magnetics, safety and compliance.

my product works fine as it is now, i am just looking for cheaper ways to make it.

Hi-Link modules are so nice in terms of price, no argument there. like 5$ for the 30w version! do you think such modules are good and safe to use? also do not produce much heat at max 22W?
current recom one is fantastic in all terms, heat, performance and so on.it has everything included in terms of input protection too.

right now i am doing a saturn power supply which i used Mornsun module. it is about 5-6$ vs the Hi-link module which is <3.5$. both require external components.

the current market of retro psu replacements do not like chinese stuff, labelled as low quality. do you think hi-link ones are good quality?

How about just have a DC input and include a wall wart with the product?

tons of solutions in the market like this and people do not like them. the idea is plug-and-play high quality, safe, universal, power supply replacement

[NiHaoMike]

I guess just get some of the cheap ones and do some testing on it? The big ones I can think of are thermals under load and a hipot test from primary to secondary. Should be pretty straightforward to make test jigs for those and randomly test a few units from each batch received if you're concerned about them cheaping out the design in the future.

[xvr]

Mornsun is a quite respectable manufacture. All there modules certified and has very good documentation. But be aware that many Chinese manufacturers making clones of these modules (under its own names).
HT-Link also made certified modules, but it less known for public and its documents not so high quality (and mostly in Cheese). I think these modules can also be used, but they require some testing beforehand.

[VEGETA]

I designed another PSU for Sega Saturn using Mornsun module: https://www.mornsun-power.com/html/pdf/LS15-23B12DR3.html

still not finished but I think of replacing it with Hi-Link one if it is high quality. I can do testing for prototype unit but cannot do that for each batch. all other batches will be produced and sold.

I have designed a good input protection circuit for the Mornsun one following datasheet maximum recommendation, please check it in attachment. I can use the exact same one for the Hi-Link. It also uses resettable fuse protection after the module (12v output) for extra layer of protection.

If I made a PSU like that, what would the tests be? I have an electronic load where I can use it to draw current at rated or above to see thermal behavior and then to see if short circuit protection works...etc those are the ones i can think of.

Hi-Link ones are of a price I cannot neglect anymore. Like for my Dreamcast power supply, instead of about 24$ for Recom one I can get Hi-Link one for <5-7$! if I put my own protection (like in attachments) then I guess it will give exact same protection and safety, just without the medical certifications.

is it a good move?

EDIT:

HLK-30M12C is about 4.12$ in 100 quantity, 86-88% efficiency which should be good enough not to generate heat. especially that i will run it at maximum 22w not 30w.

there is this HLK-40M12 GaN module claiming 91% efficiency but nearly double price, not worth it for me to get this at this price.

[Haenk]

From a business POV - does it make sense to redo the design?
If you are doing a production run of 40pcs. - and maybe save 200$, while going from a "known good" design to "who knows how good this will be" - where is the savings? Assuming you could earn some money elsewhere, or use that time to design another project.

[VEGETA]

From a business POV - does it make sense to redo the design?
If you are doing a production run of 40pcs. - and maybe save 200$, while going from a "known good" design to "who knows how good this will be" - where is the savings? Assuming you could earn some money elsewhere, or use that time to design another project.

it costs me around 45-50$ to make, I sell it for 85$ and this is the first batch so I will see how it sells. it is expensive for sure, and selling to retailers will reduce profits.

Making it significantly cheaper means i can sell it for less and gain more profit.

I am already making another project which is a power supply for Sega Saturn, in this one I will try putting Hi-Link module since it is very very cheap tbh. saturn is rated at 10-12w and the power module is about 15w so much room available. with my protection circuit i think it will be fine. will do some tests for sure.

many solutions are there in this market but none provide a universal plug-and-play same formfactor like i do. plus low noise, very low heat, high quality...etc I want to keep doing this at same level.

If Dreamcast PSU is sold for 70$ instead of 85$ it will be huge as no one would get the other solutions since they will cost about the same. assume 70$ selling price and now about 30$ cost if using cheaper module... means 40$ profit. while now 85$ - 50$ = 35$ or so.

I think I will see what performance it will deliver in Saturn PSU when I do prototype, then will do a prototype for DC.

[jonpaul]

Rebonjour:

Exactly what is this product, market, sales area eg US, UK, EU, Worldwide?
What is the load?
Safety and EMI compliance needed or ignored?

I would estimate  3..6 months.. to design, protp, debug and get compliance and get delivery on any DIY offline SMPS.

For modules suggest  the many USA old line firms   eg Lambda.

 Nowadays  99.9% of  elctronics   made in  Commi china , USA major brands   use better fab, parts and QC than any CCP junk.

We like and have bought many from Lambda/TDK USA

https://www.us.lambda.tdk.com/products/acdc-power-supplies/pcb-mount.html
Avail from DK
https://www.digikey.com/en/products/detail/tdk-lambda-americas-inc/PH50A280-12/4519350

Bon chance,

Jon

[VEGETA]

Rebonjour:

Exactly what is this product, market, sales area eg US, UK, EU, Worldwide?
What is the load?
Safety and EMI compliance needed or ignored?

I would estimate  3..6 months.. to design, protp, debug and get compliance and get delivery on any DIY offline SMPS.

For modules suggest  the many USA old line firms   eg Lambda.

 Nowadays  99.9% of  elctronics   made in  Commi china , USA major brands   use better fab, parts and QC than any CCP junk.

We like and have bought many from Lambda/TDK USA

https://www.us.lambda.tdk.com/products/acdc-power-supplies/pcb-mount.html
Avail from DK
https://www.digikey.com/en/products/detail/tdk-lambda-americas-inc/PH50A280-12/4519350

Bon chance,

Jon

it is a power supply for retro gaming console, market is worldwide but mostly USA. No compliance or anything needed, just the confident that the product works fine without any safety problems.

those lambda modules are very expensive, no way i can use them in such a product.

[Terry Bites]

see
https://webench.ti.com/power-designer/switching-regulator?powerSupply=1
for some ideas. It will give you the magnetics design too. You can farm out transformer winding to a third party.
I'm thinking that I'd farm out the whole project to a Shenzhen Prototyper to maximize my margin. Get a quote or thousand!

If you want to sell into international and domestic markets you need to show EMC and safety compliance for the device as a whole.

[VEGETA]

see
https://webench.ti.com/power-designer/switching-regulator?powerSupply=1
for some ideas. It will give you the magnetics design too. You can farm out transformer winding to a third party.
I'm thinking that I'd farm out the whole project to a Shenzhen Prototyper to maximize my margin. Get a quote or thousand!

If you want to sell into international and domestic markets you need to show EMC and safety compliance for the device as a whole.

Power.com already gives detailed transformer design, all it remains is to make it. this one i forwarded to prem magnetics but they still didn't respond.

I created everything else, since i can do it cheaply and in high quality. please check the product link above.

as for selling, i will be selling via my own website which delivers to people via mail shipping... and via some known distributors which never ask for any certifications. they sell other solutions which are less quality too,.

[jkostb]

Within the EU it is mandatory that your product complies with one of the relevant safety standards. If you can not prove that your product meets these safety standards, then it is forbidden to sell these products within the EU. The construction of a flyback converter is critical for safety in particular when it is powered from the mains. If you have sold products where you did not perform a safety assessment, then it might have legal impact.

The same applies for EMI/EMC. You need to verify that your product meets EMC standards. You are not allowed to sell your product without testing. EMI certification by a lab can easily cost 10K. The safety assessment you can do your self, but you need to have experience with this

Another thing to take into account is that custom designed transformers usually require minimum order quantities (>1000?). So for this reason if your sales volumes are low it is probably better to keep using modules of Recom, Traco, TDK Lambda and if you want really low price have a look at  Mornsun. Be care full with chinese power supplies. I have seen many cases where the module combined in product did not comply with radiated and/or conducted emission tests. You need to add extra components in order to pass emission tests.

[VEGETA]

Within the EU it is mandatory that your product complies with one of the relevant safety standards. If you can not prove that your product meets these safety standards, then it is forbidden to sell these products within the EU. The construction of a flyback converter is critical for safety in particular when it is powered from the mains. If you have sold products where you did not perform a safety assessment, then it might have legal impact.

The same applies for EMI/EMC. You need to verify that your product meets EMC standards. You are not allowed to sell your product without testing. EMI certification by a lab can easily cost 10K. The safety assessment you can do your self, but you need to have experience with this

Another thing to take into account is that custom designed transformers usually require minimum order quantities (>1000?). So for this reason if your sales volumes are low it is probably better to keep using modules of Recom, Traco, TDK Lambda and if you want really low price have a look at  Mornsun. Be care full with chinese power supplies. I have seen many cases where the module combined in product did not comply with radiated and/or conducted emission tests. You need to add extra components in order to pass emission tests.

if i use a module like recom or hi-link, those who are certified and verified... will i need to get testing again? or is it enough?

please look at above circuit where I used and put all input protection possible for ac-dc module. besides that i don't think there is much to do. please check

[jkostb]

Hi

I have following remarks regarding your flyback circuit:
1) You need to know the leakage inductance for proper dimensioning of your RCD clamp. Leakage inductance is completely determined by construction of your transformer!
2) Does your product belong to class 1 or class 2 safety class?
3) As always with reference circuits, you need to spend additional thoughs about EMI filtering. There is a big chance that this design will fail conducted emission tests. There is a big chance that the 0.33nF capacitor is not sufficient to pass these tests.
4) I don't see any surge protection at the input. All EMI standards have some form of surge testing at mains.

[mariush]

You spend so much money on the AC power supply and then you go with some SamYoung electrolytic caps  ... at least that's what I think they are... can't even read a series on them, so who knows what they are.  Maybe NXP because it's the only yellow series on lcsc ... but they print the series on the label on that one.

Why would you even need 3300uF worth of capacitance, aren't you using buck regulators running at high switching frequency to produce 5v and 3.3v?  Not sure it makes sense to have so much capacitance...

1200-1500uF 16v solid capacitors from good brands are like 30-50 cents each

[VEGETA]

Hi

I have following remarks regarding your flyback circuit:
1) You need to know the leakage inductance for proper dimensioning of your RCD clamp. Leakage inductance is completely determined by construction of your transformer!
2) Does your product belong to class 1 or class 2 safety class?
3) As always with reference circuits, you need to spend additional thoughs about EMI filtering. There is a big chance that this design will fail conducted emission tests. There is a big chance that the 0.33nF capacitor is not sufficient to pass these tests.
4) I don't see any surge protection at the input. All EMI standards have some form of surge testing at mains.

the design was automatically done by power.com using innoswitch3 after i gave them the specs needed. however, please look at my circuit in attachment for input protection for a Mornsun (or Hi-link) power module. it has all recommended input protections done.

as i mentioned, i have very simple way of doing stuff. i designed this awesome power supply around recom power module (+ my own buck regulator circuits after it) and had only 5 in stock as test batch. all sold instantly even without me advertising it. i made a quality power supply for the market which demands it. it is for sega dreamcast console... a true better replacement of original power supply which excels at everything and provide better performance.

i plan to make this and sell it via my personal website + 2 big retailers in the small niche market (retro game consoles). absolutely no certification or paid tests will be done... i just don''t have enough money to do them. these retailers never asked for anything either.

maybe what you guys say apply when i want it to be soled at a bigger level or more mainstream... but this niche i don;t think it would matter.

You spend so much money on the AC power supply and then you go with some SamYoung electrolytic caps  ... at least that's what I think they are... can't even read a series on them, so who knows what they are.  Maybe NXP because it's the only yellow series on lcsc ... but they print the series on the label on that one.

Why would you even need 3300uF worth of capacitance, aren't you using buck regulators running at high switching frequency to produce 5v and 3.3v?  Not sure it makes sense to have so much capacitance...

1200-1500uF 16v solid capacitors from good brands are like 30-50 cents each

caps are samyoung NXH series: https://www.lcsc.com/product-detail/Aluminum-Electrolytic-Capacitors-Leaded_SamYoung-Electronics-NXH-25V3300-16-25_C359208.html

not bad ones, 105 degrees 10k hours low esr. i needed big caps to eliminate last bit of noise. i saw them being used in apple chargers + did research and read about their specs before using them. my go-to for good quality and cheap were Lelon RZW but these were better.


i think if i enhanced the layout just a little more i will get better result without big caps... someone told me so after giving him the layout and a unit, he said i need to let the return current be forced to return to output caps negative side first then all the way to source...instead of having ground vias everywhere like i do now. plus i have 2nd stage filtering which i think can be eliminated as well.

i will try his suggestion in my next project which is saturn psu, and if it worked better then i will revise this design to make it better.

i did use some good low esr solid polymer caps but weren't enough for 3.3v rail at 3amps due to layout not fully optimized. thus bigger caps were the compromise i did to solve it for that version and it did.