I hereby certify that I am not simply asking someone else to design a footprint for me.
I’m trying to find a footprint that’s a 24-QFN with a 0.4mm pitch, but can’t seem to find it in the KiCAD 7 library. This is for use on the CYPD3177-24LQXQT USB-C PD controller chip, which, according to the datasheet is 24-QFN but with pins on 0.4mm centers. When I place the CYPD3177-24L chip on my schematic (this is the only CYPD3177 chip in the library), it seems to be linked to a 24-QFN footprint, with 0.5mm pitch.
When I just go to the PCB editor, I can add 24-QFN 4x4 footprints, but they all have 0.5mm pitch.
Am I just overlooking the 24-QFM 0.4mm footprint somewhere, or do I have to go ahead and create it myself?
Thanks for your responses.
-Kevin
I’m not sure this question is valid. I got out a loupe and my finest ruler, and it looks like to me that the pins are on 0.5mm spacing. I think the datasheet is wrong.
Can anyone confirm that the pins are 0.5mm spacing, or should I continue in my quest for a 24-QFN with 0.4mm pitch?
Thanks.
-Kevin
By default, KiCad does indeed link to a footprint with a 0.5mm pitch, and this is the same as stated in the datasheet. In the datasheet on page 24 there is a drawing of the IC. The lower case e is the pitch of the pads:
And in the table just under it. it specifies e as “0.5 BSC”. BSC is an abbeviation of Basic Spacing between Centers, and it is a nominal measurement without tolerances. Note 1 specifies that all measurements are in millimeters, so there is also no ambiguity in that department.
Everything added up, both KiCad the documentation and your own measurement seem to be correct and apparently you just looked at the datasheet while not fully awake yet, or too late in the evening
@paulvdh, thanks for responding.
Point 1: Yes, there are footprints with 0.4mm spacing, but no 4x4 footprints with 0.4mm spacing.
Point 2: Yes, you’re absolutely correct. I looked at the capital ‘E’ entry of 4.00 BSC (and mis-read that), rather than the lower-case ‘e’ entry of 0.5mm. I can’t even find ‘E’ on the diagram:
