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  • TI Thinks Resolved

AC-DC Conversion Selection Guide

Intellectual 410 points

Replies: 6

Views: 444

Hi

I want to design a adapter which should be able to work on universal Input (85-265V AC, 50/60Hz) and output should be either 5V/12V and current requirement is 2A, 3A & 5 A.

I have searched TI site and found there are so many solutions available and i do not know which solution should i use. I don't need PFC or any kind of great technologies. I want to make it simple as possible. Please guide me with reference design and which technology should i use to design the same.

Thanks in advance for your help.

Thanks

Krunal SHah

  • Hi Krunal,

    I have asked on of our engineers to respond to your post, you see a reply soon.

    Regards

    Peter

  • In reply to Peter Meaney:

    Hi krunal, are you trying to design different adapters, with different output specifications, or one adapater, capable of meeting all the output requirements listed.

    If it is the latter, how will the output voltage be selected? Will the feedback resistors be chosen for a specific output voltage, or is it required to be able to switch from one voltage to the other without changing components? If so, how would this be done, with a mechanical switch, with a single from an MCU, some other way?

    If you require one design to cover all the requirements then it will not be very well optimised. A design which can supply 5A @ 12V (60W), can also supply 10W (2A @ 5V) but the effiiciency, size and cost will all be adversly affected for the 10W solution.

    For the 2A and 3A deisgn, the UCC287xx family can be used, either the UCC28740 if opto feedback is required, or the UCC28704 if not.

    For the 5A design, the LM5023 or UCC2863x have higher gate drive capability and may be more suitable. All of these IC's have EVMs which target similar power and output voltages to what you mention.

    See http://www.ti.com/tool/PMP4489 as one example.

    Billy

  • In reply to Billy Long:

    Dear Billy

    Thank you so much for your reply & sorry for the confusion.

    Actually i am trying to design individual power output. my exact requirement is 12 Volt with different current output like 2Amp, 2.5Amp, 3 Amp and 5 Amp in individual boards.

    While searching i found that transformer which is used in these kind of adapter has minimum height of 16mm and my allowable height is 13mm*15mm in the enclosure so i thought if i use 5V,2A output circuit twice and connect them in series to get 10v 2amp instead of 12V.

    So in nut shell can you help me to design a adapter which can give the output of below in individual circuit/board with maximum height of component is not greater then 13-15mm.

    1) 12V, 2Amp (I can add two 5V, 2Amp circuit in series to get this output)

    2) 12V, 3Amp

    3) 12V , 5Amp

    Thanks

    Krunal Shah

  • In reply to Krunal Shah94:

    I wouldn't recommend putting two power supplies in series. In theory it should work but I think you could run into problems in current limit, startup, etc.

    For adapters with height restrictions like you mention I would look at using EFD cores for the transformer, which are designed to be low profile. The EFD 30/15/9 such as this datasheet, en.tdk.eu/.../efd_30_15_9.pdf should work for the 60W application, and smaller sizes for the lower powers. They should also meet the 15mm height requirement you are shooting for, probably even the 13mm requirement.
    Hope this helps.
    Thanks
    Billy
  • In reply to Billy Long:

    Dear Billy

    Thank you so much for quick response.Can you suggest few reference design for my different requirenement where i can use EFD 20/10/7 or EFD 25/13/9
     because they are best suitable for my height requirement. I have searched few of them as below let me know if i can use any of above in that design instead of given one in the design



    www.ti.com/.../PMP9638

    www.ti.com/.../PMP10276

    www.ti.com/.../PMP6740

    www.ti.com/.../efd_5F00_25_5F00_13_5F00_9.pdf:1230:0]

  • In reply to Krunal Shah94:

    Hi Krunal, chosing the correct core requires knowing several parameters such as the inductance, peak current, turns ratio, desired efficiency, peak flux density etc. The following link presents the authoritative explaination and derivation on the subject. ecee.colorado.edu/.../Ch14slides.pdf

    Unfortunately these calculations are not pubished with the designs above so it is not possible to say you can drop one core or other into a particular design, and in any case the transformer would still need to be designed.
    I would recommend using the design calculator given on the product webpage to design your board and calculate the parameters required to design your transformer, per the Kg method described above.

    Thanks
    Billy

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