ADS7953: Footprints of ADC (ADS7953) vs Ethernet PHY DP83822

Good afternoon Tom (or should I say "good morning" to you in the USA?)
Thank you for the reply.

However, based on your own statement, I need to know the following:
For the ADS7953 the package description is as follows:

and for the DP83822 it is as follows:


These were taken from the respective datasheets that I mentioned the references of earlier today.
My first response is to say that the two devices are packaged the same. But then this begs the question: Why are the PCB footprint drawings different? In addition, are the differences important? If the differences are indeed important, then which is the correct footprint? This is extremely important for to get reproducibility right.

Please advise.

Thank you very much

Meyns

Yep!  Still morning here in TX.  If you look at the product folders under the Package | Pins | Size option, you will see that both devices point to the latest mechanical drawing for the VQFN (RHB) package.  Both are pointing to https://www.ti.com/lit/pdf/mpqf130d  And, embarrassingly enough, that drawing does not actually have any dimensional detail!  Will try to rectify that ASAP.

Good morning Tom

I apologise for responding only now; had a few other issues to resolve.

Should I wait until this matter is finally resolved before progressing with my PCB footprint exercise, or should I continue just as is? Will you please advise me once the referenced document MPQF130D is corrected? I am currently hung with my design until this is resolved, or at least hon how I should proceed.

Thank you very much

Meyns

Good afternoon/morning Tom

I agree that the packages are nominally the same, but the footprints that must be used on the PCB for these two devices differ according to their respective datasheets. And THAT is my issue. That is why I asked the question initially whether these differences in the PCB footprints are important for proper mounting, assembly and operation of (in my case) the DP83822.

Please check below what I found regarding the PCB land aspects.

Feature                                     DP83822 (SLNS505E)      ADS7953
Overall footprint tip-to-tip      5.4mm                                5.8mm
Single contct land length         0.6mm/0.25mm                 0.85mm/0.28mm
Centre pad length/width          2.9mm/2.9mm                   3.15mm/3.15mm

In addition, there is a difference in the geometries of th contact lands between the two devices: The geometry of the contact land of the ADS7953 is rounded beneath the IC, whereas that of the DP83822 (to SLNS505E) is not.

What I need to know is whether these differences are important. Because if they are not, it may mean a problem free production run when building the PCB subassemblies in quantity. Or if these differencs are important, it may need a redo of the PCB altogether to rectify production issues if the same footprint were used for both devices.

Thank you very much.

Meyns

Hi Meyns,

I think you are looking at an older datasheet of the ADS7953, the current version is SLAS605C and the land pattern is on page 78.  From page 113 of the SLNS505E, I see now that the center heat slug is different.  If you wanted to use the same PCB footprint for both devices, I suggest that you use the 2.9 mm dimension of the DP83822 device.