DP83848K: Question for schematic

Lee, Sam

Part Number: DP83848K

Hi team,

In below DP83848K schematic, is it possible to remove the resistors on TXD/ RXD data lines when the length between MAC and PHY is short?

What is the side effect when removing it?

Thanks,

Sam Lee

over 7 years ago

0 Aniruddha Khadye over 7 years ago

TI__Mastermind 18425 points

Hi Sam,

It is recommended to keep the resistors there. The resistors are used for proper termination, without them there can be impedance mismatch leading to signal reflections. If customer want to remove them, they will have to perform their own testing to check if this works for their application.

-Regards,
Aniruddha

0 Lee, Sam over 7 years ago in reply to Aniruddha Khadye

TI__Expert 6215 points

Hi Aniruddha,

Thank you for your answer. For RMII mode, is it also reconmended to use the same resistor values?

Thanks,
Sam Lee

0 Aniruddha Khadye over 7 years ago in reply to Lee, Sam

TI__Mastermind 18425 points

Hi Sam,

For DP83848K, yes they will be needed in RMII as well. For both MII and RMII, I would recommend starting with 33ohms and if that is showing problems then increase to 47ohms.

-Regards,
Aniruddha

0 Lee, Sam over 7 years ago in reply to Aniruddha Khadye

TI__Expert 6215 points

Thanks Aniruddha.

Best Regards,
Sam Lee

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DP83848K: Question for schematic