Hi people, i am new here.
I want to create a library for the TI tlc5927. It has a lot of connections,
so I decided to learn to use the command line: SMD, PAD, etc.
I explain step by step what I've done.
Component's datasheet:
http://focus.ti.com/docs/prod/folders/print/tlc5927.html
STEP 1: Read the datasheet and look for the information about the pins,
measures, recommended footprint, etc. I have marked in red the information
that I use.
What I need are the dimmensions of the pads and the big thermal pad (in
red).
STEP 2: Calculate the relative positions of every pad referring to the
origin (blue cross in the picture). I use a excel sheet to calculate easily
the position of every pad, like:
STEP 3: With this Information I prepare a file .scr that will create the
footprint automatically.
Quote:
Thermal pad
SMD 7.8 3.4 (3.9 0);
Upper row
SMD 0.44 1.74 (0.325 -2.8) (0.975 -2.8) (1.625 -2.8) (2.275 -2.8)
(2.925 -2.8) (3.575 -2.8) (4.225 -2.8) (4.875 -2.8) (5.525 -2.8) (6.175
-2.8) (6.825 -2.8) (7.475 -2.8);
Lower row
SMD 0.44 1.74 (0.325 2.8) (0.975 2.8) (1.625 2.8) (2.275 2.8) (2.925
2.8) (3.575 2.8) (4.225 2.8) (4.875 2.8) (5.525 2.8) (6.175 2.8) (6.825
2.8) (7.475 2.8);
Silkscreen
LAYER tPlace;
WIRE (0 -2.25) (7.90 -2.25) (7.90 2.25) (0 2.25) (0 -2.25);
STEP 4: I run the file .scr and y then I have the next footprint:
There are a couple of things that I still have to solve:
- How do I change the solder mask for the thermal pad? According to the
datasheet, I should let a small "windows" as shown in the first picture.
- The vias are still pending.
Thanks in advance!
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