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SOIC DTMF encoder/decoder IC needed

Discussion in 'Electronic Design' started by Phil in Melbourne, Sep 19, 2007.

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  1. Hi all,

    I'm looking for a DTMF encoder ic and a matching DTMF decoder IC.

    The ones I have seen use a serial interface bus but I am after discreet
    binary output.

    I am aware of the Motorola MC145436 but it seems that this chip is going out
    of fashion. (Farnell and RS dont stock it any more)

    Any ideas?
  2. DTMF chips are definitively obsolete, as everybody is now doing DTMF
    generation and detection by software. The easiest solution would be I think
    to use a low cost microcontroller with built-in analog resources, like the
    PSoC from Cypress (in particular as the PSoC Designer development tools do
    support DTMF generation, and as applications notes exists I think for DTMF
    detection...). The smallest chips will probably be enough.

    Robert Lacoste
  3. There is no need for a dedicated DTMF chip.
    The DTMF encoding and decoding is perfectly done by a microcontroller.

    Vladimir Vassilevsky
    DSP and Mixed Signal Consultant
  4. mpm

    mpm Guest

    Try Google on "CML Micro".
  5. Joel Kolstad

    Joel Kolstad Guest

    ....and, for detection, often not as well as the dedicated ICs did. There were
    a lot of clever techniques used back then to avoid falsing and really dig
    signals out of the mud, whereas if you look at the app notes for doing it in
    software today, the quality tends to be all over the board. Many don't even
    use the old Bell Labs test tapes that were specifically designed to
    characterize the quality of a decoder.

    Granted, with almost all phone calls going digital except for the last bit of
    analog between a home and a concentrator/central office, lower quality DTMF
    decoders aren't as much of a problem as they once might have been.
  6. Jim Thompson

    Jim Thompson Guest

    See the PDF of my patent...

    4,472,816 FSK Discriminator


    Nothing quite beats analog for pulling signals out of the noise.

    ...Jim Thompson
  7. Guest

    1500 parts contain DTMF in their description on the DatasheetArchive

    Hope these are useful.
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