DP83867IR: DP83867 RX_CLK and RXDx voltage is lower than 2.5V

Betty Guo

Part Number: DP83867IR

Hi team,

Customer use DP83867 communicating with their CPU iMX6DL, and use RGMII mode. The voltage of VDDIO is 2.5V. the waveform as below:

Blue is TXD singal; yellow is RXD signal, the VDDIO voltage is 2.5V. you can see that the RXD voltage only have 1.36V. could you give some ideas about this？

Is it because the driving capability is not enough? do you have some suggestions? thank you. here is the schematic of customer.

over 6 years ago

0 Hung Nguyen92 over 6 years ago

TI__Expert 5670 points

Hi Betty,

Under which condition did you measure the TXD and RXD signals? Where did you probe these signals?

I'm not sure why you see 2.5MHz clock signal on TXD and 25MHz clock signal on RXD. If there is a way to disconnect the CPU from the DP83867, please do so and provide the waveform coming out from RXD pins of DP83867.

Regards,

Hung Nguyen

0 Betty Guo over 6 years ago in reply to Hung Nguyen92

TI__Expert 7300 points

Hi Nguyen,

my understanding is that, under the RGMII mode, the RXDx and TXD clock signal should be 125MHz, right?

you suspect that the CPU may cause the voltage level? we will disconnect the CPU to check the RX_CLK and RX data. thank you

0 Hung Nguyen92 over 6 years ago in reply to Betty Guo

TI__Expert 5670 points

Hi Betty,

I haven’t heard back from you, I’m assuming you were able to resolve your issue.

I will go ahead and close this thread. If you need further support, kindly open a new thread.

Regards,

Hung Nguyen

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DP83867IR: DP83867 RX_CLK and RXDx voltage is lower than 2.5V