SparkFun Forums

[JimWright]

Hey folks, if there's a better place to post this, please feel free to point me in the right direction.

I'm a noob at Eagle, and at this point it seems that I'm not going to have enough time to really figure out how to make it do what I need, so I'm putting out a call for some help.

What has me stumped is that I need to use a component that I can't find in an existing library, specifically a TI TPS2511, a USB charge port controller. This particular chip uses a PowerPad package, and requires vias for thermal dissipation, and preferably a good bit of copper top and bottom to help with this. I've found the basic package design in Eagle, but nothing that includes the thermal vias I'd need.

I'm hoping to find someone that can whip up a library with this chip. I'm building a multi-port iPad/iPhone/etc charging station. I think I should be able to do a small board with two of these and a dual USB port fairly cheaply, I'd need two such boards for my project.

[Ross Robotics]

The thermals is just small vias placed close together. And the copper is probably just the ground planes. Let me take a look at the datasheet and I get back with ya.

Did you want someone to design the board or just the TPS2511 footprint?

UPDATE: Just looked at the footprint in the datasheet and it's just a standard thermal pad underneath. But, I still would put some thermal relief vias under and maybe beside it.

[JimWright]

Hey, Codlink. I was thinking that at least two vias should be able to fit under the chip, I found other PowerPad chips in Eagle, some had vias, some didn't. Since this chip will have 2.1a flowing through it, the better the path for heat to escape, the better.

I should have put in my original post that I'm not looking to pay anyone anything for this, I was just hoping to find someone wanting to stretch their Eagle wings a bit in a way that right now I can't. If you're interested in doing the whole board, that would be fantastic, but it's up to you. I'm planning to have the boards made by oshpark.com, $5 per square inch and three copies. Their design guidelines are here: http://www.oshpark.com/guidelines

Since it needs to fit in a small space, I was planning to use a double stack USB port, like the Cypress CCUSBA-32002-15, http://www.cypressindustries.com/pdf/CC ... 002-15.pdf, but it turns out that Eagle doesn't have any double staked USB connectors in its libraries either. I've found single, triple, and quad, but no double... Anyway, I figure I should be able to get two ports on a 1" square board without too many problems, once I have libraries for the parts I need, that is. LOL

[Ross Robotics]

Yep, that's why I said to put some vias around it as well. I understood that you weren't paying anything, I like working with Eagle and seem to want to design my own boards than to buy them already made.

I have done alot of business with OSH Park. I wrote a CAM file fust for them. I have one board that should be getting shipped in the next few days and another one that was just sent to the fab house.

What is your maximum size for the board, and I need all the specs that you have. Have you started a schematic? Is that the specific USB port that you will be using? I can make the Eagle library for it.

I will start making the footprint for the TPS. But, I will need all the specs for your project. The more info the better..

[JimWright]

On the USB port, I'm not locked into a particular manufacturer, but a double stack port will be the best use of the available board space. Here are two other options:

http://www.jameco.com/webapp/wcs/stores ... 2076551_-1
http://www.parts-express.com/pe/showdet ... er=320-251


The specs that I have are:

1" square board
Dual USB ports
Qty 2, TPS2511
Pads for Resistor between each TPS2511 Pin 2 and GND
Pads for Resistor between each TPS2511 Pin 5 and VCC
Pads for Capacitor between each TPS2511 Pin 8 and GND
Pads for Capacitor between each TPS2511 Pin 3 and GND
Thru hole solder pads for +5v and Gnd connections to board, use two of these per board so I can chain power to the 2nd board from the first.
Mounting holes on each side of the USB connector, can attach to GND but not required.

I'm basically using what's in the data sheet, and it doesn't seem that any additional parts are really needed.

On the Out line (pin 8), add a thru hole solder pad somewhere, and another on the GND for each chip. I might add an LED on the case to indicate the port is active.

I can't think of anything else unless you spot something in laying things out. Thanks!

[Ross Robotics]

OK, I will see what I can come up with. Should be done by Sunday so you can have a look. I don't know much about the chip either, but I have the datasheet. When I have it done I will post the schematic and let members see it for a second pair of eyes.

Oh, btw, you need to be careful on how you type on the forums. I see your smilie with sunglasses. I think you meant "pin 8" But correct me if I'm wrong.

[Ross Robotics]

I am also going to need what size parts you want.

[JimWright]

Sorry about the smiley above, yes, I meant pin 8.

Figure 5 on the data sheet has the following values show:

Pads for Resistor between each TPS2511 Pin 2 and GND, 20k
Pads for Resistor between each TPS2511 Pin 5 and VCC, 100k
Pads for Capacitor between each TPS2511 Pin 8 and GND, 22uf
Pads for Capacitor between each TPS2511 Pin 3 and GND, .1uf

There should also be a 100k resistor between pin 4 and Vcc, according to fig 5.

[Ross Robotics]

I meant what "size" components, not value. SMD, thru hole?

[JimWright]

Sorry about that. Thru hole is fine, except of course for the TPS2511 itself.

[Ross Robotics]

Screen shots of the top and bottom and together of the board.

NOTE: This design is the 10W Switched version.

[Ross Robotics]

Attached is the schematic and Eagle files.

[JimWright]

Hey there, looking good. One issue, though, is that the mounting holes on either side of the USB connector were left off. I need the board to be securely anchored at the USB so that it can hold up to being plugged and unplugged.

You can get a bit more real estate back by having the USB port pads nearer the edge of the board, so that the port hangs off the edge of the board. The resistors can also mount radially and save a bit of room too, if that helps the design. The ICs could probably also move a bit further in which will get a bit more copper on the upper part of the board, which could improve heat dissipation.

Last thing, from the graphic posted (I have Eagle on my work system so can't check the file directly) the thermal vias at the top of the chips seem to be closer to the edge than the vias on the bottom (as viewed on the graphic). May just be how the graphic was generated? May not matter, or maybe that's the best that Eagle can place them? I'll check it tomorrow when I get to work and see what it looks like if you haven't replied before then.

Excellent work!

[Ross Robotics]

I posted the Eagle files so you can adjust it like you want. I have done the hard work, least you can do is finish it up.

[JimWright]

No problem! Again, I appreciate all of your work here.