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TO220 switchmode 7805T replacement?

Discussion in 'Electronic Design' started by [email protected], Feb 17, 2007.

  1. Guest

    I think something like this
    http://focus.ti.com/docs/prod/folders/print/pt5101.html
    looks good, but I didn't check the pinout or the physical
    compatibility. I think it's bigger than a TO-220.
     
  2. budgie

    budgie Guest

    Looking for info on available drop-in switchmode replacments for the 7805T
    regulator, for a 250mA-sized load. Have located the RECOM series, but I'm
    wondering who else does this type of device.

    Tnx for all leads.
     
  3. John

    John Guest


    http://www.national.com/pf/LM/LM2576.html
     
  4. Gibbo

    Gibbo Guest

  5. John  Larkin

    John Larkin Guest

    A couple of people do make tiny pc boards or potted gadgets that are
    dropins. Can't remember who, but google should turn them up.

    John
     
  6. Gibbo

    Gibbo Guest

    Eh? Did your copy and paste not work properly?

    tlc5620 - "quadruple 8 bit digital to analogue converter"

    Or was it a joke that I missed?
     
  7. That may be true if you want physical and well as electrical
    match. But if you have the space for a slightly bulbous
    replacement and perhaps, the need for an additional
    capacitor across the output and possibly some extra input
    voltage, there are some choices. i.e.:

    http://focus.ti.com/lit/ds/symlink/tlc5620.pdf
     
  8. Gibbo

    Gibbo Guest

    Nice!

    Data sheet saved, Cheers.
     
  9. Not as easy as you might think, since the same key words
    bring up so many integrated circuits and other references.
    I knew this one existed, but still had to go back through
    earlier correspondence to find it.
    http://www.cd4power.com/data/meters/dms-78xxsr.pdf
     
  10. TI's former Power Integrations, or was it Power Trends? stuff:
    http://www.ti.com/lit/gpn/pt5101 Only $12.25 each at DigiKey,
    stocking 7911 of the A, 3338 of C, and 1238 of the N packages.

    The N package (outline EAD) stands up like a TO-220 LM7805 linear
    regulator, except it takes up more floor space, 0.42 x 1.06 inches,
    and 1" tall. The pcb can have four holes to position it properly.
    I'd want an additional mechanical securing of some kind, Sheesh!
    Are you allowed to drill any holes? Here are the EAA EAC and EAD
    package drawings, http://www.ti.com/sc/docs/psheets/mechanic/E.htm
     
  11. Very nice, much smaller than TI's part. It does 0.5A at 5V,
    compared to 1A for TI, but the small size is awesome. $9.90,
    Newark no inventory (74-day leadtime), but Mouser has 'em.
     
  12. budgie

    budgie Guest

    Wow, some of those devices have footprints like elephants!

    The application is a batch rework of an existing product which uses a 7805T so
    there simply isn't the wad of room around it for any of these 1" wide jobs, nor
    the headroom for tall ones.

    Unfortunately the orig design was poor both thermally and physically. The
    un-sunk 7805T runs way too hot (although it doesn't go into shutdown). It is
    placed away from the pcb edge and among other components. The board is in a
    plastic case so a heatsink connected to the case - apart from not being possible
    - wouldn't do anything, and a clip-on sink isn't going to help, as it is still
    going to dissipate the same energy into the same confined airspace.

    The rework solution has to get the heat dissipation down. Switcher.

    The RECOM product I located
    (http://www.recom-international.com/switching_regulator_R-78xx.html)
    will just fit in the available space, but before committing to that I was
    hunting for others of a similar size which may have had better
    price/availability.

    Thanks guys for your input.

    P.S. The designer HAS been *told*.
     
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