PCB Layout Guidlines for Ethernet?

I'm looking for PCB guidelines as well, such as Board type, recommended trace width, etc...

I'd like to third the request. I'm looking for any reference designs for the 3s811, but I'd take general schematic suggestions or layout suggestions.

I'd like to add my voice to this. EVB schematics are nice, but don't offer the necessary detail.

We have an application note planned for board layout recommendations. When it is ready, I will post a message indicating it can be downloaded.

We also need some more information regarding the selection of the ethernet magnetics. There are a lot of choices out there and virtually no guidance with respect to the particular needs of the Luminary PHY.

Put another way... Can anyone tell me what factors were used in the selection of the part used on the LM36965 Evalutation Board? It uses a Pulse J3011G21DNL - See http://www.pulseeng.com/products/datasheets/J409.pdf

Here is one source of info. See the curious comments on slide 46 of http://www.scvemc.org/files/Ethernet_Magnetics_EMI.pdf
(his diagram seems reversed, however)

Is there a better choice of information out there?

DeanErickson wrote:


Put another way... Can anyone tell me what factors were used in the selection of the part used on the LM36965 Evalutation Board? It uses a Pulse J3011G21DNL - See http://www.pulseeng.com/products/datasheets/J409.pdf

Here is one source of info. See the curious comments on slide 46 of http://www.scvemc.org/files/Ethernet_Magnetics_EMI.pdf
(his diagram seems reversed, however)

Is there a better choice of information out there?

His diagram isn't reversed, it's just a different kind of magnetics design. The Pulse J3011G21DNL is of the "2-Line CM Choke on the Cable Side" kind, as shown on slide 63 of the presentation.

Still waiting for that application note, Luminary...

Post edited by: matten, at: 2008/06/26 08:04

Hi,

This is my 1st post, so, excuse if it sound stupid...

we are ready to develop PCB board using LM3S6911.

I could not find enough information to complete the schematic.

I planing to use the EKT-LM3S6955 to program/debug my 'going to be developed board'

My development tool will be Code-Red.

My question,

Can anyone please provide example schematic which has the following;
1. programmable via EKT-LM3S6955 evaluation kit
2. UART Port(Rs-232, 115Kbps)
3. Interface to SD card (micro)
4. I2C line connected to DS1307+ (RTC chip)
5. LAN Interface (recommended suitable magnetic)
6. 10-GPIO

I can take care the regulator, reset, crystal, 232 line interface and other external module.

I need support on which pin/port need to be used on the above requirement.

I know what I am asking to a lot, you assistance is highly appreciated and when you are in Malaysia, I take you for beer... ;-)

The full schematic for the EKB-LM3S6965 eval kit is actually in the user manual. As far as I can tell, this board contains everything on your list with the exception of the I2C RTC module but the I2C is not used on the board so it should be very straightforward to add it yourself.

If you want to download the manual, you can find it on this page. It's also on the CD that comes with the 6965 board.

Please post a reply if there is anything else you need.

TI - Eric Hewing

We have an application note planned for board layout recommendations. When it is ready, I will post a message indicating it can be downloaded.

 

I figured after 2.5 years this would be done.  Is there an app note?

When it comes to routing  differential eth lines standard rules apply (short tracks, continious return path and controlled impedances)

for a standard 1.6mm FR4 four layer pcb an adequate trace width of 0.22mm with 0.2mm spacing will result in

approximate Zdiff of 100 (5-10% tolerances depending on your manufacturer) for a differential microstrip. What

I usually do is to make a rough estimate of the single ended impedance of the track and use it to make a plot

of resulting differential impedance versus track separation, then I pick a width space ratio that looks sane. After the

layout is done and I'm about to send my odb/gerbers into production I specify the parameters of the stackup and

impedances (frequency range as well), so the pcb manufacturer can refine my design (if necessary) since they know their

production capabilities much better, they also run an impedance test on the produced pcb to verify the target impedance.

 

Hope this helps.

 

Taking a look at the datasheet for any ethernet enabled uC tells you that the following Isolation transformers will work (and Jacks with magnetics):

■ Isolation Transformers
– TDK TLA-6T103
– TDK TLA-6T118
– Bel-Fuse S558-5999-46
– Halo TG22-3506ND
– Halo TG110-S050
– PCA EPF8023G
– Pulse PE-68515
– Valor ST6118
– YCL 20PMT04
■ Isolation transformers with integrated RJ45 connector
– TDK TLA-6T704
– Delta RJS-1A08T089A
■ Isolation transformers with integrated RJ45 connector, LEDs and termination resistors
– Pulse J0011D21B/E
– Pulse J3011G21DNL

No App note  still!! Wow! Great!  More than 2 years gone.

Amazing!  I just stumbled upon what looks like the appnote many people have been waiting for - AN01283 - System Design Guidelines for Stellaris Microcontrollers.   Seems incredible that basic info like this is only now coming out.

http://www.ti.com/litv/pdf/spma036