Question about Lan transformer

Hello Hong Jieun

Thank you for the query.

The MDI signals are differential signals. 

Regards,

Sreenivasa

Hi Sreenivasa,

Thank you for your replying. 

I know that MDI signals are differential signals, but what if RX+ signal of RJ45 is connected to RX- signal of PHY. 

Regards,  

Hello Hong Jieun

This is taken care by MDIX. ( straight or cross cable configuration)

Are you working on a project and having some issues? 

If not, if you are looking to understand the functioning i would suggest reading ethernet information available on the web.

If you do not have further questions, please close the thread by pressing resolved button.

Regards,

Sreenivasa

HI Sreenivasa,

In my project using 100Base-TX Ethernet, I connected RX+ of RJ45 pin to RX- of PHY pin. 

But I find it operates normally contrary to my expectations.

I wonder why it's working normally.

Is there any function to correct polarity or it doesn't matter if it connected it like this? 

Hello Hong Jieun

This is taken care by MDIX. ( straight or cross cable configuration)

Please refer to the datasheet of the device you are using. You can share a PDF schematics as required.

Regards,

Sreenivasa

Hi Sreenivasa, 

As far as I know, MDIX is used when the connection between RX and TX is cross.

Does MDIX also apply to RX+ and RX- differential signals?

Regards,

Hi Sreenivasa,

According to DP83849 Cable Diagnostics, polarity reverse does not require correction at 100Mb. 

Is this because of MDIX?

Then why isn't it 10Mb?

Regards,

Hello Hong Jieun

Each device follows the required ethernet standards and also provides additional functionalities.

This is a feature provided by DP83849 and is explained well.

The features are device dependent.  I do not have additional details to provide. 

Please share the schematics  and the issue you have if you need further support. 

Regards,

Sreenivasa