DP83825I: DP83825i traces impedance

Lenna Yan

Intellectual 1960 points

Part Number: DP83825I

Hi Expert,

In the 11.1.1 signal traces section, it's said that all single traces should be 50 Ohm single-ended impedance. In customer's application, they add a 22 ohm resistor at the trace, just as in the below figure. I want to know if the 22 Ohm resistor are included in the 50 Ohm impedance.

over 6 years ago

0 Geet Modi over 6 years ago

TI__Mastermind 26320 points

Hi Yan,

Subject of your query indicates DP83825 but your question is for RGMII which is not supported by DP83825. Can you please provide the correct part number ?

Regards,

Geet

0 Lenna Yan over 6 years ago in reply to Geet Modi

TI__Intellectual 1960 points

Hi Geet,

Yes. DP83825i doesn't support RGMII, it's a common question. The figure here just wants to show the 22 Ohm resistor, not the PHY device itself. DP83825i support RMII. I want to know if adding a 22 Ohm resistor on the trace, is the 22 Ohm resistor contained in the 50 Ohm terminal impedance?

0 Geet Modi over 6 years ago in reply to Lenna Yan

TI__Mastermind 26320 points

Hi,

PHY has internal terminations of 50 ohm, however you keep the series resistor as place holder to take care of any tuning needed on the RMII interface.

Regards,

Geet

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DP83825I: DP83825i traces impedance