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Logic Level Translator

Discussion in 'CAD' started by Jim Thompson, Nov 1, 2005.

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  1. Jim Thompson

    Jim Thompson Guest

    There was a series of posts in the past few weeks concerning
    translating a 3.3V logic level into 5V logic.

    I have posted here...

    the basic concepts, and also created a simulation mockup using the
    venerable CD4007.

    This structure consumes no static power other than leakage.

    There is some "kinkiness" in the waveforms. I don't know if it's due
    to the long channel-length of the CD4007 devices or the VERY poor
    device models (Level=1 and Level=2 was all I could find).

    I've done this trick quite successfully on custom chips where I could
    scale the devices to suit my needs.

    Maybe someone will construct this with a CD4007 and report back?

    (Beware, wire exactly as shown... pin 14 must go to +5V to prevent
    tub/body diode conduction.)

    ...Jim Thompson
  2. Joerg

    Joerg Guest

    Hello Jim,
    But this consumes a good half of the chip for just one data line.
    There I could see it. You don't have to sacrifice another SO or TSSOP
    package there.

    I usually do it discrete. I'd try anyways but have to do some math right
    now. Filter algorithms ... blech...

    Regards, Joerg
  3. Jim Thompson

    Jim Thompson Guest

    It consumes the whole CD4007, since the associated N-channel devices
    are tied off.
    I was just demonstrating the principle.
    Have fun ;-) (Analog or digital?)

    ...Jim Thompson
  4. Joerg

    Joerg Guest

    Hello Jim,
    Digital this time which is why it's not that much fun. The real
    disappointment came when I happily perused today's offerings of DSP and
    found out that the ones with 16bit codecs on board have gone AWOL. So
    now I'll have to figure out how to schlepp 14-15 rather unorthodox
    single-bin DFTs through a uC or bite the bullet and use a TMS320 plus
    external ADC. These DFTs can't all have the same sampling frequency
    which makes it even less fun with an off-chip ADC. This is also why FFT
    wouldn't work here. The other challenge in this project is that the
    classical and expensive DSP books here on the shelf fall quite silent
    when it comes to weird filters.

    The good news is that the uC world has made much more progress than DSP
    since I last used one. You can get 16 bitters with hardware multipliers
    for under $5 a pop. And you don't have to spoon-feed them their code
    from an EPROM anymore. Nice.

    Regards, Joerg
  5. John Fields

    John Fields Guest

  6. Jim Thompson

    Jim Thompson Guest

    Of how a logic level translator is designed.

    Can't you read?

    ...Jim Thompson
  7. Jim Thompson

    Jim Thompson Guest


    The "kinkiness" comes from lack of gain in the feedback. Change
    74HC04 to 74HC14 and it becomes letter perfect.

    I'm still refining it, but you can also do a similar (more current
    consumptive) trick using a single 74HC14 wrapped around with a PNP
    current mirror. Consumes current rather than being zero at the end
    states, but it's cheap on parts.

    ...Jim Thompson
  8. Jim Thompson

    Jim Thompson Guest

  9. Jim Thompson

    Jim Thompson Guest

  10. Robert

    Robert Guest

    Why can't you see this (and others you've posted) documents when I go to and then select the SED link?

    I prefer to download PDFs then open them rather than doing that in a

  11. Jim Thompson

    Jim Thompson Guest

    I can link them into the SED cover page if you like. I tend to link
    only circuits that should be of more universal interest.

    Can't you set your browser to download rather than open? In Firefox
    you can.

    ...Jim Thompson
  14. I read in alt.binaries.schematics.electronic that "Rich, Under the
    Rich, Acrobat Reader is, and always has been, free.
  15. Chuck Harris

    Chuck Harris Guest

    Taken a level further, Adobe Acrobat, works on Windoze, and Linux,
    and is as John says, free.

    But you can also get ghostview, which works under Windoze, linux,
    and the unixes, free.

    and xpdf, which works under linux, and the unixes, free.
    and kpdf which works under linux, and the unixes, free.
    and gpdf, which works under linux, and the unixes, free.

    And since killing a dead horse is fun, you can author pdf's
    using, which runs uner Windoze, linux, OSX, and
    the unixes, and it is, free.

    Seems to me, that the "rich folk" are the ones using the microslop
    products. The whole rest of the world is using linux.

    But not to worry, someday soon, the "rich folk" will be using linux

  16. Bob Monsen

    Bob Monsen Guest

    There is an acrobat reader 7.0 version for linux... Sadly, it has all the
    same annoying flaws as the windows version..

    FC4 has 'evince', which, while having a buggy display engine, is far
    quicker, and displays lots of different types of documents as well.

    Bob Monsen

    All things which can be known have number; for it is impossible for a thing
    to be conceived or known without number.
    - Philolaus (Pythagorean)
  17. Bob Monsen

    Bob Monsen Guest

    On Sat, 05 Nov 2005 07:47:04 -0500, Chuck Harris wrote:

    Hey chuck.
    Unfortunately, it isn't the 'rich/poor' dichotomy; it is the 'no time to
    waste/lots of time to waste' dichotomy. Linux requires far more time
    fiddling with things than windows. Downloading drivers, upgrading kernels,
    getting samba and wireless to work properly, etc, etc, is time-free on
    windows (if it works at all), whereas Linux demands an investment in
    learning and time that many would consider prohibitive.

    It is the same as mac vs dos back before windows. The folks who liked to
    fiddle with their computers thought mac was a sissy OS, because it didn't
    support all the tweak knobs they loved. The mac guys were generally into
    doing other things with their time, and so thought the nerds were wasting
    their time.

    However, sadly, this time thing is often belied by some horrific problem
    with windows, that requires DAYS to fix, if it is even fixable. So,
    perhaps the time argument balances out, or the rich folks can afford to
    simply hire somebody to do the windows grunt work.

    As a guy who likes to fiddle with things, I enjoy Linux. However, I have
    lots of time on my hands these days...

    Bob Monsen

    All things which can be known have number; for it is impossible for a thing
    to be conceived or known without number.
    - Philolaus (Pythagorean)
  18. Robert

    Robert Guest

    Thanks. Didn't know that was an option in Firefox. Set that way now.

  19. Chuck Harris

    Chuck Harris Guest

    Except that it doesn't. Most people couldn't run windoze if it didn't
    come preconfigured on their new computer. There is absolutely no reason
    that linux couldn't come that way too. I preconfigure linux systems for
    family and friends, and they don't have any problems.

    I got my mother running linux amd she doesn't know a damn thing about
    computers. She has the suite for typing letters, XMMS to
    play her CD's, Mozilla to handle the internet, and the card game suite
    that comes on KDE. It does everything she used to do on windoze, ...
    well almost everything: I haven't had to fix a thing on her machine
    since I changed her off of 'doze. No more late night calls about the
    machine not responding, or not being willing to shut off, or ...

    The only time she goes back to 'doze is to run taxcut to do her taxes.
    And then the complaints about the crashing come back!

    Level the playing field Bob, give potential linux users the same
    slack you give 'doze users... a preconfigured machine.

  20. JeffM

    JeffM Guest

    Level the playing field Bob, give potential linux users
    Here's one problem with that: Which distro?
    (Bottom-of-the-line hardware)
    Another problem:
    Non-M$-fanboyz don't like to feel like they're getting schnookered.

    You can't even get a computer WITH NO OS
    that's not more expensive than one with Windoze.
    **Dell Offering "Open" PC***-*-17-LCD-monitor-*-*-*-*-*-for-*-same-price

    Can you say "Penfield"?
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