PCB Design first time - will appreciate a quick look


I just finished a pcb consisting of 9.1cm diameter circular shape that I want to send out to a manufacturer…
It has an Atmega328, 3xTLC5940, 16LEDS
2 potentiometers, 1 breakout board sound sensor

I checked the manufacturer design rules for holes, minimum sizes etc and i am OK on that.

I’d appreciate a quick glance if there are things like traces that can should be near one another, or any problematic issues with grounding/impedance/VCC crossing improperly etc… (not whether the ICs’ pins are routed correctly for example)

I included several images, next time I will use eagle for sure…

  1. top view (attached)
  2. top view with ground fill on top only (attached)
  3. bottom view with ground fill on bottom only (attached)
  4. top view with ground fill on bottom only (attached)
  5. Top view with SCLK,XLAT,BLANK,GSCLK pointed out (http://postimg.org/image/x9jt84ne7/)

Trace widths:
All traces 10mil, the SCLK,XLAT and BLANK are 12mil of the way, VCC are all 24mil

The brown area in the middle is basically the ground fill blocker where i am planning to put on both layers a different ground fill for the analog ponts and sound sensor

I got two things I am concerned (part of anything i am not aware of):
1. I added a lot of vias on the outer areas so any isolated copper fill will be connected to the ground fill below which is continuous,not sure if thats fine and if thats actually going to work as i think it would… there are like 2-3 areas where i am going to clear the fill from as it isnt really needed there, i just quickly filled the ground for this post purpose and forgot to clean it

2. Do I need a 10k pull up resistor on the first TLC5940’s BLANK pin. I see some designs which use it and some which not…

To be honest, I didn’t do any math calculations to see whether this would work, I based myself on other’s people designs and work so I think I should be okay, especially as I want to run the LEDs at 15ma and not 20… but I will construct this on a board as I didn’t even work on any code yet :slight_smile:

Thank you!

Didn’t you post this before? Looks very familiar.
I don’t see any issues with the routing.
Using vias to connect top & bottom ground layers is fine, I do it all the time.
Couple of the LED names are sitting on the outer grey ring, maybe move those a little. With Eagle I would Smash the part and then move the name.
Some of the names are overlapping the part outlines, I would fix those.
Some of the parts - you appear to have values there instead of a reference designater (C1, C2, etc). I would fix that.
Some of the names overlap vias. Move the names a little or they will not be readable.
It’s the little cosmetic stuff like that which makes the board look sharp when all done. Having the Ref Des for each part makes the board much easier to debug as well if needed.

Hi Crossroads,

Yes i posted about twice in the past, once with 74hc595 and tons of resistors :roll_eyes: and second time with the TLC5940.. and you gave me comments.. this is more of a last post to maybe identify last issues before i sent this over to osh park.. i am creating this for 3 different people for their birthday and im already late for all of them hahha :drooling_face:

What about the 10k pull up resistor on the first TLC5940's BLANK pin, do i need it? I didnt put one here..

Regarding he labels, i will be moving them around a bit to look better on the silkscreen, but i am actually planning on printing a rather crazy design all over it..

I am going to screenshot then use photoshop to create a whole layer of drawing that will not overlap the pins and other silkscreen elements.. (hopefully it won't look idiotic)

10K, can put pads there, not use it, if doesn't work as desired then add it.
No pads, will be hard to add.
I didn't look at the datasheet to check it out.
There are TLC5940 libraries, do they expect to drive the pin?

Yeah i am expecting to drive the leds with some sort of library…

Well, i know you didn’t see the schematic but i thought it would be easy to picture it as there is nothing special here… i would have post schematic but ever since i changed the ICs to the TLC i didn’t bother, the schematic designer in fritzing is very annoying…

  • i connected the arduino to the first tlc5940
  • daisy chained all ICs and added the resistor but didnt pick which value yet, it will be either 2.4k or 2.7k (calculated i need 2604ohms for driving each led at 15ma)
  • i have 0.1uf ceramic capacitor between any IC’s VCC and GND
    -all leds are common anode connected to VCC
    -3 analog devices (2 ponts, 1 breakout board)
    i crossed referenced information on how to do it from multiple sources

would all that matter for the 10k resistor?
do i really need different ground fill for those analog devices? the ground fill for that part(attached) comes out really broken up, with 3 extra vias for these ground fills, i think connecting one ground fill wouldnt matter much

i guess these things probably matter more for running sophisticated audio electronics no?

Screenshot_0008 2014-08-13, 01_08_19.jpg