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JST-XH connector - which way round?

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5件のコメント

  • Brad Levy

    This connector series is available in top entry and side entry versions.
    The footprints are different between the two.

    On the top entry version the pins are closer to the side of the housing with the keying slot(s).

    Here is what the datasheet says about mounting recommendations:

    Notes on my interpretation of the datasheet:

    They recommend the holes be at least 3.4mm from the edge of the board for the top entry version.

    On the side entry version, they recommend the row of pins be 9.2 mm from the board edge.
    The drawing above shows a 1 mm hole for the pins on the top entry version, 0.9mm hole on the side entry version, but has a note recommending a larger hole size for harder PCB board materials. (The pins have a retaining kink/bulge which interacts differently with the harder PCBs.)

    It looks like you are using the side entry version, with a footprint with 1.35 mm holes.

    The pins (and footprint holes) are closer to the back side of the side-entry connector housing than to the side the mating connector plugs into. So it looks like you have it rotated 180 from the way you want it, assuming you want the opening on the right.
    Beware that the footprint you are using doesn't include the entire area covered by the connector.
    I've roughly shown the area it appears to cover here:
    So if you don't want the connector to overhang the edge of the board, make sure the centerline of the pins is at least 9.2 mm back from the board edge.

    The square indicates pin one. (The break in the outline on the silkscreen is there to indicate the location of pin 1.)
    That said, while some connectors have specific pin numbering, frequently molded into the connector itself, other connectors (like this one) do not. Starting from the left end (looking down or into the connector) is sensible, I didn't see anything on the datasheet that indicates the manufacturer defines that pin order.

    Likewise, apart from application-specific connectors like USB or SATA, most connectors do not define what pins power and ground will be on. Sometimes the power pins will be a different size for greater power handling, but that isn't the case here. I'd probably add labeling on the board silk screen to inform the users of the correct polarity.

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  • Jennifer Smith

    Thanks Brad, that's really helpful.  Never thought to check the datasheet for the board positioning and didn't realise it didn't show the full connector.  

     

     

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  • Brad Levy

    Yep. I don't have time today but it would be good for someone to have a discussion with the Samacsys about why the part outline in the library doesn't include the full part for the side-entry connector. And about doing some sort of labeling on the several top-entry models, to indicate which ones are designed for hard PCB materials (larger holes) vs soft PCB materials (smaller holes), since the average user is just going to be puzzled as to why there are several different entries for the same component.

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  • Boss .

    Just out of interest what is the full part number are you searching. My quick look for JST-XH showed many results but for the different number of pins.

    Regarding updates as Brad states Samacsys are very responsive to improvements to component models.

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  • Brad Levy

    Hi Boss,

    Jennifer is using the 2-pin part, and I presumed from her earlier post about flat connectors that she is using the side-entry version rather than top entry. S2B-XH-A. RS #5469050 for quantity-10 packs.
    (There is also a S2B-XH-A-1 version that has a shorter shroud depth, listed on the same data sheet. But it is less common, and doesn't show up in a Samacsys search.)
    Two PCB footprints show up in the search for the S2B-XH-A. They have different Samacsys IDs, but are (at least nearly) identical in hole size, etc.

    The hole size on the B2B (top entry version) parts on Samacsys is different than on the side entry, though the data sheet show recommends the same unless using a different PCB material.


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