Problems with LM2596 Layout

parts help
1

Hi folks,
I’m not sure, if the post belongs here or some other category, if wrong, please notify me and move it.

I built a word clock and wanted to create an own PCB for it.
For the power supply I used a DC-DC step down buck converter, here the LM2595 DC-DC buck converter. For my layout I decided the fritzing part from “Robby”, the “LM2596 step down module”.
I routed the PCB and sent it to Aisler to get 9 PCB’s done, which I received wednesday.
After soldering I found out, that there is no function at all.
As being a present, I had to switch back to an experimental board, which worked at the first spot.
I took some time today trying to find the problem and found, that there is a problem with the layout from Robby. There are two pins switched: V out+ is where V out - should be and otherwise.
The part itself look the way it should:

grafik

but the pins are dfinitely changed

grafik

grafik

The rest ist working, but the PCB’s are completely useless, cause I have a double layer with copperfilling for ground.

First: Does anybody check the layouts, before they are given to the crowd?
Second: How can I change the layout to eliminate the problem, cause I want to build some more of the clocks with my PCB layout.
Third: I’m pretty upset, cause I ruined around 50€ and quite a day finding the problem.

Is there some help for me?

THX in advance!

Freddie

2

Best bet is upload the sketch (the .fzz file, upload is 7th icon from the left in the reply menu) so we can have a look at it. It is also a good practice after producing the gerber files to display them in a gerber viewer (I typically use gerbv, but there are a lot available) to make sure the layout is right. In Fritzing gerber creation happens after pcb view rendering so if there are bugs in the gerber code (or incorrectly configured parts which appears to be the problem here) there may be problems. If it doesn’t appear in the gerber output it won’t appear on the board.

Peter

3

Hi Peter,
here is the part…

LM2596 step down module.fzpz (24.2 KB)

THX for your fast reply!

Freddie

4

For me the part appears to work fine and generate correct gerbers on 1.0.5 on Win10

capture
capture886×834 94.3 KB

capture1
capture11431×828 92.3 KB

It doesn’t match your images above which show one ground pin greyed out though. The sketch that is breaking would likely be more useful.

Peter

5

Hi Peter,
thank you for the time you invest to help!

On the first look, you’re right! Everything looks fine, but if you open the part editor and take a look at the pins, you find out, that the pins fr V out + and V out - are swapped…

I selected the V out +, which should be in the top line, but the dashed border proofs, it’ in the bottom line, see pic 1; LM2596 V out +, check dashed border line of pin
I also selected the V out -, please check pic 2; LM2596 V out -, check dashed border line of pin

Open the LM2596 module out of the Fritzing Project I attached to this post with the parts editor and switch to the PCB View, then double click on the pins for V in and out, you see the problem. The layout of the LM2596 should be the way, that the V in + and V out + should be in one line at the top of the part and the V in - and V out - should be in one line ath the bottom of the part.

Wort_Uhr_2.1.fzz (101.8 KB)

I finally decided to create a small test scetch and this is the result:

LM2596 Test.fzz (27.0 KB)

IMHO this shows, that the pins are definitely positioned wrong in this layout.

Do you have any idea how I can solve this?

I found a workaround for the PCB’s I already have, but this will only work for clocks I will give away as a present.
Is there a way for me, I can change the pins?

THX in advance…

Freddie

6

Yes, I didn’t check it quite closely enough. It has the pins out of order in the svgs so I went through and cleaned it up entirely and created this new part. I changed the pcb hole sizes to be 0.038in (the size for a 0.1in header) I think they were probably a bit larger before if that matters to you they can be changed. I didn’t change the moduleId so you will need to delete the current part from your parts bin and then shutdown Fritzing answering yes to save parts and save parts bin (save sketch you can likely answer no to.) and then restart Fritzing to really remove the part. You should then be able to load this new part

LM2596 step down module-fixed.fzpz (14.4 KB)

Peter

7

Hi Peter,

thank you very much for your time!
I’m happy, that I found the problem and could help others not to go the same way…
I tried to swap the pins in the Parts Editor but this is a book with seven seals for me.

Freddie

8

While I think parts editor should be able to do this, it rarely works for me so I don’t use it. I just edit the files directly which is much easier.

Peter

9

I tried to change a few parts several times, but had not the efoort I wanted, so finally I gave up. Now, since I’m retired I have a little more time to spend, so I will try again and find out about the mysteries…
:slight_smile:
Freddie

10

These two tutorials may help out. Both apply to current Fritzing versions. Retirement rocks! I have been retired for 15 years now.

I lately learned there aren’t links to the videos in Old_Grey’s tutorial so you need to do a google search for the title and then they come up on YouTube.

Peter

11

THX for the links and hints!

Yes, I really love this episode of my life! A lot of things I want to do…

Freddie