DP83848C: Connect only 10 Mbps to Poe Switch

mustafa uygun

Part Number: DP83848C

Hello,

I have issues on the ethernet phy device DP83848.I encountered an interesting problem in POE design. I use "tenda tef1109p" poe switch. ın this switch there are 2 mode defult mode and extend mode.

I can run our design only extend mode. In extend mode this ethernet switch working 10Mbps. But defult mode support 10-100 Mbps.
In our ethernet design with DP83848 without POE we can connecting this switch in defult mode.
Why POE desing with DP83848 cant connect with ethernet swich at defoult mode

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over 4 years ago

0 Kallikuppa Sreenivasa over 4 years ago

TI__Guru**** 191839 points

Hello mustafa uygun

Thank you for the query. I am trying to reword your questions for clarity. Please confirm.

I can run our design only extend mode. In extend mode this ethernet switch working 10Mbps.

Can i assume you are talking about PHY ?

But defult mode support 10-100 Mbps.
In our ethernet design with DP83848 without POE we can connecting this switch in defult mode.

The PHY works when POE is not connected

Why POE desing with DP83848 cant connect with ethernet swich at defoult mode

With POE connected, the PHY does not work for 10/100. Is that correct ?

Regards,

Sreenivasa

0 mustafa uygun over 4 years ago in reply to Kallikuppa Sreenivasa

Prodigy 30 points

Hello Kallikuppa Sreenivasa

Thank you for reply.

Can i assume you are talking about PHY ?

Yes It's true I am talking about PHY.

The PHY works when POE is not connected

When the POE is connected or not, if the ethernet switch is not in extended mode, the PHY is not working and ethernet not connect. We have another hardware that has the same schematics as the ethernet schematic used in our POE design. In this design, communication can be established with a data rate of 100Mbps.

With POE connected, the PHY does not work for 10/100. Is that correct ?

With POE connected or not, the PHY does not work for 10/1000.

0 Kallikuppa Sreenivasa over 4 years ago in reply to mustafa uygun

TI__Guru**** 191839 points

Hello mustafa uygun

Thank you for the inputs.

You are using an external switch and the DP83848C does not work when connected in basic mode where as it works in extended mode.

If this is not correct please make a diagram for me to understand.

Can you please add the caps as recommended in the below diagram of the datasheet

Figure 7-2. 10/100 Mb/s Twisted Pair Interface

Regards,

Sreenivaa

0 mustafa uygun over 4 years ago in reply to Kallikuppa Sreenivasa

Prodigy 30 points

Hello Kallikuppa Sreenivasa

You are using an external switch and the DP83848C does not work when connected in basic mode where as it works in extended mode.

Yes we are using "tenda tef1109p" poe switch and DP83848C does not work when connected in defult mode where as it works in extended mode.

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0 Kallikuppa Sreenivasa over 4 years ago in reply to mustafa uygun

TI__Guru**** 191839 points

Hello mustafa uygun

Thanks for the input.

Please check making the changes to the MDI input Figure 7-2. 10/100 Mb/s Twisted Pair Interface.

The Tenda switch does not provide much information on the basic and extended mode.

You might want to also check with the tenda on this behaviour.

Regards,

Sreenivasa

0 mustafa uygun over 4 years ago in reply to Kallikuppa Sreenivasa

Prodigy 30 points

Hello Kallikuppa Sreenivasa

I have tried the configuration in Table 7.2 before. The connection problem persisted. Nothing changed.

In extend mode (10 Mbps data rate ) we get PHY adress and all responces are correct 0x01
In defult mode (10/100) we are not get PDY adress and all responces 0xFF

0 Kallikuppa Sreenivasa over 4 years ago in reply to mustafa uygun

TI__Guru**** 191839 points

Hello mustafa uygun,

Can you probe if the MDI signals are coming to the board from the switch.

You also might want to check with the switch vendor.

Regards,

Sreenivasa

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DP83848C: Connect only 10 Mbps to Poe Switch