Locating a triple output SMPS - Page 1
Forum section: electronics / general

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: December 13, 2011, 10:14:05 am
content: Im searching for a triple output SMPS:+5 V - 5 A+12 V - 3 A+24 V - 2 AMeanwell has units with this ouput voltage but usually the 12 V is limited to 0.8 A on average. The current ranges listed are minimal required.

author: Psi
author_rank: Super Contributor
timestamp: December 13, 2011, 10:17:00 am
content: 220V or 110V input?Found this on digikey, but with "Call for price" i bet its expensive++http://search.digikey.com/nz/en/products/NLP150L-96T658/393-1044-ND/409796RS have quite a few that would work for you but most are quite expensive.Here's the cheapest ones.Note: This is RS New Zealand so prices are in NZ dollars.http://newzealand.rs-online.com/web/p/embedded-power-supplies/6295535/http://newzealand.rs-online.com/web/p/embedded-power-supplies/4182409/

author: ejeffrey
author_rank: Super Contributor
timestamp: December 13, 2011, 11:42:01 am
content: You could get a 5V / 24V supply and a separate DC-DC converter that takes the 24->12 V. Alternately you could use an ATX power supply plus a boost converter to get your 24 V from 12, but you will have to watch out for the minimum load currents.

author: Unknown
author_rank: Unknown
timestamp: December 13, 2011, 01:06:38 pm
content: Quote from: hacklordsniper on December 13, 2011, 10:14:05 amMeanwell QP-320D +5V - 2.5 to 20A , +12V -0 to 10A, +24V 0.2 to 5A, -12V 0.2 to 2A $244.00AU list, about half that trade. The 5V and 24V need some load all the time. If you have the space 3 discrete SMPS modules are going to be lots cheaper and Lots more flexible.http://www.meanwell.com/search/qp-320/qp-320-spec.pdf

author: ivan747
author_rank: Super Contributor
timestamp: December 13, 2011, 02:25:14 pm
content: Quote from: ejeffrey on December 13, 2011, 11:42:01 amI second the ATX power supply option. Cheap and readily available. Thee are many boost converters out there that can handle 2A. You also get a remote power off line as well as a standby power rail. You can also use the -12V line for powering things that require negative voltages. It is also easily replaceable. Just be aware of the minimum load requirements.

author: Zero999
author_rank: Super Contributor
timestamp: December 13, 2011, 05:53:33 pm
content: Is where the 0V rail is connected critical for the 24V load? If not, you could use an ATX PSU for that too. If the 24V device needs to be switched, a P-channel MOSFET could be connected in series with the +12V rail and the negative connected to -12V.A word of warning: with an ATX PSU make sure you have fuses on the secondary side as the short circuit current can be high enough to start a fire.

author: ejeffrey
author_rank: Super Contributor
timestamp: December 13, 2011, 06:18:31 pm
content: Quote from: Hero999 on December 13, 2011, 05:53:33 pmThe -12 V rail usually has a very low current limit, plus this makes the 5V supply not work.

author: Zero999
author_rank: Super Contributor
timestamp: December 13, 2011, 07:03:52 pm
content: What's the typical current rating of the -12V supply? If it's under 2A I can see that being a problem but how does it stop the +5V supply from working? It doesn't.It makes no difference to the 5V supply. The only issue may be interfacing between the 24V and 5V circuits but that may not be required.

author: McMonster
author_rank: Frequent Contributor
timestamp: December 13, 2011, 07:18:00 pm
content: Quote from: Hero999 on December 13, 2011, 07:03:52 pmATX PSUs usually have their outputs grouped with maximum allowed output power per group and that's the only limit I can think of.

author: Psi
author_rank: Super Contributor
timestamp: December 13, 2011, 10:27:51 pm
content: Quote from: Hero999 on December 13, 2011, 07:03:52 pmI think he means, if your using -12 for GND to get +24 on the +12 rail then +5 is really +17VBut yeah, the -12v rail is usually very low current, its not all that useful except to drive opamps.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 13, 2011, 10:37:25 pm
content: Could you use multiple power supply modules or derive some rails using a DC/DC converter?

author: ejeffrey
author_rank: Super Contributor
timestamp: December 13, 2011, 11:18:50 pm
content: My computer's power supply is 0.8 amps at -12 V. I was assuming the system required 5/12/24 all relative to a common 0VDC. This means both that there would be no 5V supply and that the -12 rail would have to handle current from both the 12 volt and the 24 volt rails. Sure that was an assumption but it is usually true in practice.

author: Psi
author_rank: Super Contributor
timestamp: December 14, 2011, 12:18:54 am
content: Also the -12 is often -10V on most PC psus

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: December 14, 2011, 06:06:15 am
content: Quote from: Uncle Vernon on December 13, 2011, 01:06:38 pmI avoided this more expensive range of power supplies since they give out much larger current than i need. But i have no choice, i cant use PC PSU and i cant use 3 separate PSU (like im doing now) because the device failed some kind of testing from the customer and they request to have a single power supply.

author: BravoV
author_rank: Super Contributor
timestamp: December 14, 2011, 06:26:56 am
content: I'm not sure how comfortable are you buying from Chinese seller through site like Aliexpress, there are plenty of these cheap Meanwell switching power supply that has multiple outputs that is really fits to your requirement.There are gazillion of examples out there like this one which has 5V@8A, 12V@2.5A and 24V@ 2A->http://www.aliexpress.com/product-gs/461708642-120W-Triple-ac-dc-switch-power-supplied-CE-approved-meanwell-style-Free-shipping-Guaranteed-100-T-wholesalers.htmlMost the times when I bought these kind of cheap ps, I usually ended with replacing their caps with better one like Jap's caps to ensure reliability, and so far what I've experienced (less than 10 units) actually they not really that bad, considering the price.

author: Unknown
author_rank: Unknown
timestamp: December 14, 2011, 06:47:33 am
content: Quote from: BravoV on December 14, 2011, 06:26:56 amMeanwell Styleis not Meanwell. Not exactly top shelf but Meanwell like almost every successful manufacturer is attracting more than it's fair share of dubious copies. You pays your money and you takes your chances! I have hundreds of cheap Meanwell supplies installed that have run for years with almost zero failures. Cannot say the same for the no names. Most of the clone prices I see on eBay are still well above the trade prices for the genuine article.

author: BravoV
author_rank: Super Contributor
timestamp: December 14, 2011, 07:00:26 am
content: Quote from: Uncle Vernon on December 14, 2011, 06:47:33 amHa..ha.., UV, you're right, I should mentioned it Meanwell "SYTLE" instead of Meanwell, sorry, my mistake.Of course the original Meanwell still far superior than these dubious copies, but as I said, from my limited experiences with these clones, after the caps replacement, they perform flawlessly even at harsh environment at full load, maybe I'm lucky.

author: Unknown
author_rank: Unknown
timestamp: December 14, 2011, 07:28:06 am
content: Quote from: BravoV on December 14, 2011, 07:00:26 amExactly, how often do you see "just like Fluke" printed too.QuoteI've had a good run with them, mind you a bit of conservative selection does wonders too.QuoteThat is pretty much par for the course. These things are sold for amazingly low prices, price up a DIY 60VA SMPS sometime. The caps are the obvious weak point. My problem is that although it is a trivial repair the cost of warranty replacement of a single supply is enough to blow away any profit once you factor in the travel, labour etc. Particularly with the sub 100VA units it's not even worth considering alternatives at any price. The supply our OP was after is a little more difficult to find.

author: johnwa
author_rank: Frequent Contributor
timestamp: December 14, 2011, 08:05:21 am
content: Quote from: BravoV on December 14, 2011, 07:00:26 amThat is worth knowing - I just bought a 27V 350W unit for use as a float charger. Can't really complain for $45 including delivery. It has worked OK so far, but I haven't had it anywhere near full load yet. Perhaps I had better put some new caps in it though.

author: bombledmonk
author_rank: Regular Contributor
timestamp: December 16, 2011, 02:53:45 pm
content: Rediculously priced option, but Excelsys has modular configurable supplies. Type your numbers in here and you'll get a same day shippable custom modular power supply out.http://ordering.digikey.com/ProductGuides/Excelsys.aspxHere was my output.Quantity Part Number Price1 XLB-01 $179.521 XG7 $83.981 XG8 $99.902 XG4 $212.22Total $575.62