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12V Down to 5V — Parallax Forums

12V Down to 5V

MacTuxLinMacTuxLin Posts: 821
edited 2012-01-09 08:23 in General Discussion
Hi,

What is the most efficient IC for such task? DC-DC converter? Any advice on part#?

Thanks.

Comments

  • kwinnkwinn Posts: 8,697
    edited 2012-01-08 19:20
    Lots to choose from. I have used the LM2675 with good results. Up to 1A and 96% efficiency. Also requires a minimum of external components.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2012-01-08 19:34
    I've used the LM2575 a lot, but seeing kwinn's post above, the LM2675 has better efficiency and smaller components. Thanks kwinn!
  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-01-08 19:37
    Hey, 96% is great. Thanks too kwinn!
  • TubularTubular Posts: 4,726
    edited 2012-01-08 20:22
    This one came across my desk today and looks good for under $10 (3 Amps @ 5v output)
    Artesyn LDO03C-005W05-VJ
  • kwinnkwinn Posts: 8,697
    edited 2012-01-08 21:51
    There is also the LM7576 if higher current is needed. Up to 3A output. Also uses a minimum number of components but efficiency is lower (75 – 90% range). I have not used this one but it is very similar to the 2575.

    BTW – Layout is very important. Follow the guidelines on page 9 of the National data sheet for best results.

    @Tubular – That is a great deal since it is a complete module. The LM2675 is $4.98 Canadian from DigiKey. By the time the cost of labor, the PCB and other parts are factored in the LM2675 supply costs me about $13.00 – $14.00. The Artesyn LDO03C-005W05-VJ is $10.40 CDN. Too bad the input voltage rating is only 3V – 13.8V. I need a 24V rating for lot of what I do, and like to have a 50% safety margin on top of that.

    PS - I forgot to mention that there is a layout for the fixed and adjustable SO8 (smt) regulator on page 22 of the data sheet. Those layouts work very well and can be adapted for the 8 pin dip very easily.
  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-01-09 00:25
    Tubular wrote: »
    This one came across my desk today and looks good for under $10 (3 Amps @ 5v output)
    Artesyn LDO03C-005W05-VJ

    @Tubular, Good find. I'll take a look. Thanks.
  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-01-09 00:26
    kwinn wrote: »
    BTW – Layout is very important. Follow the guidelines on page 9 of the National data sheet for best results.

    @kwinn, got it. Thanks.
  • TubularTubular Posts: 4,726
    edited 2012-01-09 00:27
    There are several switchers available in "7805" format, some take up to 72v input, and cost effective ones go to about 30v.

    The advantage is of course you can always revert to a $1 basic 7805 if your circuit/application isn't going to draw much current, or if you're going to run it from a 7~9v wall wart

    Here's the link to the Cui (72v, $11ish) and Recom (32v, $5ish) part #'s
  • max72max72 Posts: 1,155
    edited 2012-01-09 07:21
    I used the 2594, both 5.0 and 3.3V. For a 12V supply the passive components are the same.
    The inductance I use is 150uH.
    Massimo
  • MacTuxLinMacTuxLin Posts: 821
    edited 2012-01-09 08:23
    Thanks @Massimo. Reading the datasheet now.
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