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D-SUB Connector puzzle

Discussion in 'Electronic Design' started by Robert Latest, Sep 29, 2006.

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  1. Hey guys,

    this is a rather academic question because a few tens of microns don't
    matter much with those old clunkers, but still this got me puzzled:

    Looking at datasheets of D-SUB Connectores from different manufacturers,
    I find three different inter-pin distances along the rows:

    ERNI: 2.75mm
    Harting: 2.74mm for 9 and 15 pin connectors, 2.76 for the others.
    Deltron: 2.74mm
    FCT: 2.74mm

    The inter-row distance seems to be consistently 2.84mm.

    All of course are supposed to be according to the same DIN/ISO standard.
    Then there is the "US" and the "European" footprint, but I think the
    difference is the distance between the PCB holes and the front panel
    plane for the angled connectors.

    I wonder if it is really true that the 9/15 pin plugs have an
    ever-so-slightly different pitch than the others. Who comes up with
    ideas like that?

  2. Could it be that the original D type was in imperial inches, rather
    than metric, and there are rounding errors?

  3. I got the impression they designed the outer dimensions first and then
    just divided by the number of pins minus one to get the exact pitch,
    but I could be wrong about that... Originally they were cable
    connectors and most users wouldn't have known or cared much about the
    exact pitch.

    Best regards,
    Spehro Pefhany
  4. Alan

    Alan Guest

    I always understood that the 25 way connector was designed to have a
    distance of 1.3 inches between the centres of the end pins on the 13
    way side thereby giving a spacing of 0.1083(recurring)inches or approx

    I have seen it surmised that the original specifier(s)/committee made
    a boo boo by making the original end to end measurement 1.3 inches
    (for 13 pins) instead of 1.2 inches, which would have a made it a nice
    0.1inch spacing.

  5. More likely it was in US inches.

    Best regards,
    Spehro Pefhany
  6. 2.75mm ~ 13/120 inch. Strange choice.

    The russians made/copied many TTL 74xx chips, with partnumbers
    like K155. I was surprised when I discovered these have a pitch of
    2.5mm, not 2.54mm. You can still squeeze them in 2.54 sockets,
    but with a 24 pin dip it really starts to hurt.
  7. mkaras

    mkaras Guest

    For years I have worked with the D-Sub type connectors. The pin to pin
    spacing in the rows has typically been 0.109 inches. That said the
    mechanical drawings for the D-Subs from Amphenol (one of the original
    manufacturers for D_Subs along with ITT Cannon) show that the pin to
    pin center spacing for shell sizes E and A are 0.108 inches and are
    0.109 for shell sizes B, C, and D. The row to row spacing has always
    been 0.112 inches. Any other dimensional info you will see in the mm
    realm is typically round-off error.

    Many of the mechanical drawings I have referenced for D-Sub connectors
    from manufacturers do not specify the total dimension between the
    outside pins of the long row of pins. The prints are drawn in an manner
    where the center to center of the jack screw holes are specified. The
    connector pin pattern is then dimensioned to be centered either way
    from the center of the jack screw to jack screw holes.

    - mkaras
  8. European IC makers used a 'standard' pitch of 2.52 mm for quite a while,
    to accomodate both 2.50 and 2.54 mm. Their intention was presumably to
    eventually replace 2.54 with 2.50.


    Adrian Jansen adrianjansen at internode dot on dot net
    Design Engineer J & K Micro Systems
    Microcomputer solutions for industrial control
    Note reply address is invalid, convert address above to machine form.
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