+ Post New Thread
Page 1 of 2 1 2 LastLast
Results 1 to 20 of 22
  1. #1
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    How to Design 5V/12V few amps SMPS

    Hello,
    How should we start design power supply for circuit?
    like 12V/5V 5Amps/10Amps

    how to start designing of power supply?

  2. #2
    Advanced Member level 5
    Points: 9,066, Level: 22
    d123's Avatar
    Join Date
    Jun 2015
    Posts
    1,601
    Helped
    377 / 377
    Points
    9,066
    Level
    22

    Re: How to Design 5V/12V few amps SMPS

    Hi,

    Like a parrot, I'll repeat ad infinitum: Read a lot, research the subject, that's the best start, then you (or I) will understand some things, but not others, but be able to formulate more specific and therefore practical forum questions.

    You seem to know Vout and Iout. You may also have decided whether your SMPS will be mains- or battery-powered. These two points, "A" and "Z" will be a good guide as to what to study to have an idea of what "B" to "Y" may need to be.

    I suggest a way to begin designing the power supply is comtemplating whether the circuit being powered by the SMPS is analog or digital, will it function erratically with switching noise, etc? Will it therefore need for the SMPS to be followed by an LDO and/or appropriate filtering?

    Another staring point is asking oneself: Do I trust my ability and knowledge to safely implement a non-isolated PS, or should I leave that kind of project for a future occasion when I feel certain I will not a) hurt myself and others, and less importantly b) keep destroying components with ill-designed circuits?

    Looking at different SMPS topologies - and only you can do that, laziness or expecting others to fill in your learning gaps in a quickie answer isn't learning, my friend - will give insight into what you, at first, think will be the best-fit solution, never hurts to understand which are harder to provide compensation for if you're a beginner.

    To summarise, my limited knowledge suggests: check topologies, choose one, do the calculations, simulate, if all goes well, prototype or make the finished PS, otherwise, back to the top of the design stage flow diagram :)

    - - - Updated - - -

    Hi again,

    Another first step question is: What's "better" - designing the whole thing myself, or getting some fantastic $0.70 multi-purpose SMPS IC that solves maybe 50 - 80% of the design procedure?

    Along with: Have I thought the battery thing through yet...Maybe a 1.5V AA battery won't power this design, and a car battery won't make for a portable device, is there something inbetween that will be adequate, or must I accept that I need to plug this thing into a wall, or adjust my current requirements?

    IC manufacturers have a host of design tools and reference designs that should be useful. Here are links to SMPS/PSU design tools, if you're interested in looking at them, and there are many others...

    WeBench "Power supply design at your fingertips!"

    Power Supply WebDesigner "A suite of tools for designing and optimising your power supply design"

    eDesignSuite "easy-to-use comprehensive software suite"

    PowerEsim "Free SMPS Switching Power Supply / Transformer Design Software"

    Design Simulation and Device Models "a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more"

    I'm not pretending any of these tools make anything easier, some may be hard to figure out and use effectively, but there are a whole range of free tools which theoretically simplify the design stage, and usually lead to the appropriate choice of IC, saving hours of cross-comparison work.



  3. #3
    Super Moderator
    Points: 69,598, Level: 64
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    14,212
    Helped
    3248 / 3248
    Points
    69,598
    Level
    64

    Re: How to Design 5V/12V few amps SMPS

    Hi,

    How to start? --> Specify your converter.

    there are many SMPS IC manufacturers.
    They all want to sell their parts and thus they give you all information you need to choose their parts.

    They have interactice selection tools to find the optimal IC. Every IC has it´s datasheet with circuit descriptions.
    Often there are additional informations like application notes and so on.

    Klaus



  4. #4
    Advanced Member level 5
    Points: 14,187, Level: 28
    schmitt trigger's Avatar
    Join Date
    Apr 2013
    Posts
    2,369
    Helped
    770 / 770
    Points
    14,187
    Level
    28

    Re: How to Design 5V/12V few amps SMPS

    Back in the 1980s, designing a SMPS was a major endeavor.

    Nowadays like d123 mentions, all of the major semiconductor manufacturers have free, very sophisticated design software. They have full fledged online selection tools. They have full characterization of all the ancillary components, some of which, like the inductors, hold a lot design secrets. They sell evaluation boards, to test and review performance on a proven board. They give you the Gerber files for you to copy those boards. They have lots and lots of app notes.
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  5. #5
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    Re: How to Design 5V/12V few amps SMPS

    where is circuit and which component are need for design?



  6. #6
    Super Moderator
    Points: 251,556, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    43,804
    Helped
    13320 / 13320
    Points
    251,556
    Level
    100

    Re: How to Design 5V/12V few amps SMPS

    where is circuit
    Look more closely at the posts above.


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  7. #7
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    Re: How to Design 5V/12V few amps SMPS

    You may also have decided whether your SMPS will be mains- or battery-powered.
    Hiii,
    I want it to be main 220V Ac to DC for led lightning right now.
    it should be isolated from AC source to avoid shock.


    https://webench.ti.com/webench5/powe...rigin=ti_panel
    Click image for larger version. 

Name:	smps.jpg 
Views:	19 
Size:	178.8 KB 
ID:	134493
    Last edited by RETGT; 14th December 2016 at 09:07.



    •   AltAdvertisment

        
       

  8. #8
    Advanced Member level 5
    Points: 14,187, Level: 28
    schmitt trigger's Avatar
    Join Date
    Apr 2013
    Posts
    2,369
    Helped
    770 / 770
    Points
    14,187
    Level
    28

    Re: How to Design 5V/12V few amps SMPS

    There you go!
    TI's webench is a very good design software. Simply continue with the design.
    There may even be evaluation boards for the IC.
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post


    1 members found this post helpful.

  9. #9
    Advanced Member level 5
    Points: 38,224, Level: 47

    Join Date
    Mar 2008
    Location
    USA
    Posts
    6,181
    Helped
    1792 / 1792
    Points
    38,224
    Level
    47

    Re: How to Design 5V/12V few amps SMPS

    With as little knowledge as you have, I'd recommend trying
    to source a module rather than (re-)invent a supply at the
    blank-board level. There are many vendors in this space and
    you'd find them easily enough by browsing the back pages
    of any electronics design periodical.


    1 members found this post helpful.

  10. #10
    Advanced Member level 2
    Points: 4,408, Level: 15

    Join Date
    Feb 2014
    Posts
    579
    Helped
    207 / 207
    Points
    4,408
    Level
    15

    Re: How to Design 5V/12V few amps SMPS

    Right, 12V and 5V outputs are incredibly common and competitive. It's unlikely you're going to benefit by designing this yourself versus finding and buying something.

    For 220AC to 12V/5V dc at about 100 watts you're talking about something like a 2"x4" open frame which, again, is very common and easy to come by.



  11. #11
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    Re: How to Design 5V/12V few amps SMPS

    then what should be my first design of smps?



  12. #12
    Super Moderator
    Points: 28,512, Level: 41
    andre_teprom's Avatar
    Join Date
    Nov 2006
    Location
    Brazil
    Posts
    8,475
    Helped
    1078 / 1078
    Points
    28,512
    Level
    41
    Blog Entries
    6

    Re: How to Design 5V/12V few amps SMPS

    It would be not you who are designing the SMPS but the tool, you are just entering specifications as input, anyway it is allways required to have a technical backgrond in order to be able to examine the solution presented, as well as to be able make minor adjusts when necessary. Based on the history of your issues throughout this forum, you seem to have a very limited level of knowledge in several areas of electronics, so you should firstly to deeply LEARN tutorials, wiki, etc..., instead of repeatedly ask for untied questions into several topics.
    --------------------------------------------------------------------------------------------------
    Part of the world that you live in, You are the part that you're giving ( Renaissance )



  13. #13
    Advanced Member level 5
    Points: 14,187, Level: 28
    schmitt trigger's Avatar
    Join Date
    Apr 2013
    Posts
    2,369
    Helped
    770 / 770
    Points
    14,187
    Level
    28

    Re: How to Design 5V/12V few amps SMPS

    Quote Originally Posted by RETGT View Post
    then what should be my first design of smps?
    A low voltage, low power one. For instance reducing from 12v to 5v at 1 amp.

    If you select the very popular and low cost LM2675, you will find many proven circuits. Its datasheet is as close as you'll find to a SMPS course.

    Best of all, many of the inductor manufacturers already provide parts which are matched and characterized to work with such circuits.

    For instance: http://coilcraft.com/lm259x.cfm
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post


    1 members found this post helpful.

  14. #14
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    Re: How to Design 5V/12V few amps SMPS

    what is this sir?



  15. #15
    Full Member level 6
    Points: 3,336, Level: 13

    Join Date
    Sep 2013
    Posts
    385
    Helped
    156 / 156
    Points
    3,336
    Level
    13

    Re: How to Design 5V/12V few amps SMPS

    The link showing inductor manufacturers. Coilcraft inductors are expensive.
    Try in Digiky or Mouser for the same

    You may get board itself :
    http://www.ebay.com/itm/10W-DC-DC-Bu...-/281679805313


    1 members found this post helpful.

  16. #16
    Advanced Member level 5
    Points: 9,066, Level: 22
    d123's Avatar
    Join Date
    Jun 2015
    Posts
    1,601
    Helped
    377 / 377
    Points
    9,066
    Level
    22

    Re: How to Design 5V/12V few amps SMPS

    Quote Originally Posted by RETGT View Post
    what is this sir?
    Hi,

    Here is the datasheet for the LM2675, page 14 shows the list of suitable inductors and their part numbers, the link in post #13 is a link to the list of suitable parts made by the manufacturer recommended in the datasheet.


    1 members found this post helpful.

  17. #17
    Advanced Member level 5
    Points: 14,187, Level: 28
    schmitt trigger's Avatar
    Join Date
    Apr 2013
    Posts
    2,369
    Helped
    770 / 770
    Points
    14,187
    Level
    28

    Re: How to Design 5V/12V few amps SMPS

    Quote Originally Posted by RETGT View Post
    what is this sir?
    It is only AN EXAMPLE of what inductor manufacturers offer as turnkey solutions for popular switchmode ICs.

    I know that it is almost always far easier to purchase ready made units from EBAY.....but the OP wants to learn SMPS circuits. The best way in my opinion are low power devices which have been charectarized.
    You may actually spend 3X of what would have costed you to purchase a ready made module on EBAY, but the learning experience is -to use the credit card commercial- priceless.
    Last edited by schmitt trigger; 16th December 2016 at 15:42.
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  18. #18
    Banned
    Points: 727, Level: 5

    Join Date
    Nov 2016
    Posts
    161
    Helped
    0 / 0
    Points
    727
    Level
    5

    Re: How to Design 5V/12V few amps SMPS

    i can buy inductor from here http://in.element14.com/inductors

    - - - Updated - - -

    hello,
    i got this circuit
    http://www.ti.com/diagrams/custom_diagram_1_LM2675.gif

    what the diode value?



  19. #19
    Super Moderator
    Points: 69,598, Level: 64
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    14,212
    Helped
    3248 / 3248
    Points
    69,598
    Level
    64

    Re: How to Design 5V/12V few amps SMPS

    Hi,

    When do you learn to look into datasheets?

    Klaus



  20. #20
    Advanced Member level 5
    Points: 9,066, Level: 22
    d123's Avatar
    Join Date
    Jun 2015
    Posts
    1,601
    Helped
    377 / 377
    Points
    9,066
    Level
    22

    Re: How to Design 5V/12V few amps SMPS

    Quote Originally Posted by RETGT View Post
    what the diode value?
    There is a list of diode part numbers on page 16 of the datasheet. 9.2.1.2.3 Catch Diode Selection (D1) on page 15 explains how to choose the right one for your circuit.

    Two points mentioned are:

    "For normal operation, the catch diode current rating must be at least 1.3 times greater than its
    maximum average current. However, if the power supply design must withstand a continuous output short, the diode must have a current rating equal to the maximum current limit of the LM2675."

    and

    "The reverse voltage rating of the diode must be at least 1.25 times the maximum input voltage."

    So, depending on Vin, and your output current/load, you can choose a Schottky diode from that list, it won't hurt to choose one of the 3A ones, so you just need to know Vin and make sure its Vr is rated at least 1.25 times higher.



--[[ ]]--