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2.7 to 5V level shifting

Discussion in 'Electronic Design' started by Richard Hosking, Mar 11, 2007.

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  1. Dear all
    Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
    The various peripherals in the system are 5V (LCD module, programming
    interface, sensors) so it seems easiest to interface the memory. There
    doesnt seem to be a serial flash available in 5V. Lots of parallel flash
    devices at 5V but these are old and take too many lines

    One line will have to be bidirectional


  2. Lionel

    Lionel Guest

    There are plenty of multi-bit buffer that include level converters
    that'll handle 2.7V to 5V.
    How many bits do you need to convert to 5V?
  3. Eeyore

    Eeyore Guest

    Will the 2.7V flash tolerate 5V I/O ? How about a part number ?

  4. Robbo

    Robbo Guest

    Re the LCD module - it may be worth a second look at the data sheet. I'm
    pretty sure that some have 3v compatible logic i/o despite the 5V supply.
  5. Eeyore

    Eeyore Guest

    Also, since the display won't need any bidirectional lines it would be
    relatively easy to use with mixed supplies anyway.

  6. Atmel ATDB021B
    These are easily available. I am basically a hobbyist. It is preferable
    if the part is available from somewhere like Farnell

  7. Lionel

    Lionel Guest

    I couldn't find that part number on the Atmel website. Are you sure
    that's correct?
  8. Sorry AT45DB021B
  9. Lionel

    Lionel Guest

    Okay, here's the datasheet:

    The memory chip has 2 outputs & 5 inputs.
    It turns out that all the inputs are specified to be 5V tolerant, so
    you can wire them directly to your 5V logic outputs.
    And for your outputs, 2.7V is high enough that they should work fine
    straight into single 5V inputs. Easy!

    So, good news! - It looks like you won't need any level translation
    electronics at all. Isn't it nice when things work out like that? ;^)

    Best of luck with your project.
  10. Eeyore

    Eeyore Guest

    I got the right part number.

    It looks from a brief glance at the data sheet that the inputs are 5V tolerant.
    It might be a good idea to check that with Atmel to be confident.

    In which case all you need to do is ensure that you uC will recognise its logic
    1 output. That could be done with just a couple of resistors to help pull it up
    a bit..

  11. Uwe Bonnes

    Uwe Bonnes Guest

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