The central slug usually needs to be grounded. Where is the data sheet for the device?
Creating a footprint like that will probably take about 20 minutes with the Pulsonix software I use. The basic pads on the outside will only take a few seconds using the footprint wizard. I can’t believe that it will take much longer with Eagle.
leon_heller, by “central slug” do you mean the “E-PAD (case bottom)” OR the “large metal rectangular surface toward the center” which in the drawing is: Detail A ? The pinout shows Digital and analog grounds so shouldn’t I create two ground planes, one for each?
Philba, On page 19: PDB requirements, it says: Land pad architecture and spacing are consistent with JEDEC MO-220 (52-lead QFN). I’ve looked but I can’t find a 52 pin QFN in the eagle library to modify. The closest I could find was a 44 pin in the Atmel .lib “QFN44ML8X8” but I don’t quite understand all the layers. So, There are seven layers?
1: tTop
25: tNames
27: tValues
29: tStop
31: tCream
35: tGlue
51: tDocu
Why can’t I move the tCream layer by itself and how can I change all the pad sizes at once?
Looking at your figure 12, they layed out the footprint all based on the center of the 1mm hole by pin 42. Everything else can be located by adding (or subtracting) distances from here. For example, the long slots go from 0.73 to 4.8 plus 2 1mm radii, so they are 6.07 mm long. The one on the right is 3.98 minus .83 or 3.15 mm from the outer edge of the pads for pins 1-9. Unless otherwise specified, you can assume that the pins are evenly spaced and the middle pins are on the center lines of the sides.
Ok thanks everyone, I think I’ve just about got it. leon_heller, you said the central slug needs to be grounded. Should I run the AGND and DGND pins to this ground pad? Also when I’am creating the the outline for the chip with the wire tool, the lines are created so they are centered on the grid lines. To get the chip to be 8.3mm square as per the drawings, do I need to account for the width of the lines or is this taken care of in the Gerbers?
I don’t feel like downloading a PDF from MediaFire. You can export images from Eagle and upload them to a free Flickr account; even better, you can include images in your actual forum posts. You’re asking for free help, make it easy for us!
I don’t have images I can include from Eagle. I haven’t created the complete layout because I can’t figure out the dimensions as I’ve said. The PDF I’ve made using Illustrator CS2 is to large to attach in the forums and I don’t have a flicker account. Whats wrong with downloding from Mediafire? Everything is scanned for viruses ext.
Why would you draw this out rather than just mock something up in the Eagle library editor? Just give it your best guess based on the dimensions calculated from that datasheet.
If you have the chip, once you think you’ve got the package as best as you can, print it out with 1:1 scaling. Physically compare and see if the printout matches the correct part dimensions and pad spacing.
Waiting for help will also not get you very far in electronics. In 20 days of messing around in Eagle you would have come up with something, or at least familarized yourself with the program enough to understand what is being discussed.
TheDirty, Yes I do have the IC but not the lens to go with it, it’s still on backorder. leon_heller sugessted that I re-create the drawing, so I did. As I’ve said I don’t understand what’s pointing to what in the drawings, so I have no idea what some of the dimensions are. As far as printing out a 1:1, the pad size and spacing is not the issue, it’s the location of the millings and the size and locations for the keep-outs and center ground.
Macegr, I do have a fairly good understanding of Eagle now. No matter what software you’re using or how good you are with it you still need to be able to read the datasheet first.
