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ADS1256: ADS1256

Aubrey Page
Prodigy 100 points
Part Number: ADS1256


This post isn’t about the use of the ADS1256. It is about package dimensioning. I am trying to create a PCB geometry for the ADS1256 in the plastic small outline package (SSOP). Referring to the Mechanical Data page of the data sheet, I am confused by the dimensioning. I have searched for GD&T dimensioning information but that was of little help. I presume a comma substitutes for a decimal point here? What is meant by 5,60/5,00 for example? Does that mean the dimension can lie somewhere between 5.6mm and 5.00mm? Likewise for 0,38/0,22. What is meant by the symbols and dimensions contained in the box beside the 0,38/0,22 in the drawing?

Is there a TI application note on this subject? I searched but couldn’t find one.

The pin spacing of 0.65mm is close to 0.025in (.025591) but not exactly. My CAD program lists standardized packages that specify 0.25in pin spacing but at 14 pins on a size, the error would accumulate. Not much but my dimensioning must be in inches, not mm.

Thanks

  • 0
    TI__Guru* 98985 points

    Aubrey,


    Yes the comma is the radix and is the same as a decimal point. For dimensions with two numbers, as in 5,60/5,00, these note the min and max expected values for the dimension.

    I don't know of any application note used as a guide for the mechanical data drawings. All symbols are standard drafting symbols for dimensions and tolerance (GD&T). The crosshair symbol indicates a position or location. The circle around M is Maximum Material Condition Modifier and refers to a feature-of-size that contains the greatest amount of material, yet remains within its tolerance zone. The arc symbol with a straight line across the bottom is for surface profile.

    I think the box next to the 0,38/0,22 with the crosshairs means that the standard distance from the center of the pin is 0,15 meaning that the typical width is 0,30.


    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 100 points

    Thank you. I think I'm clear now.