DP83TC814S-Q1: Crystal

Hi Ivy,

When 25Mhz crystal is used for PHY, RMII master mode should be selected. The image you have pointed out has a typo. This was corrected in DP83TC812 datasheet, and will be carried forward to DP83TC814 datasheet update on next revision. Please see DP83TC812 datasheet Figure 9-2.

Thanks,

David

Hi David,

Thanks for your comments!

Add a question:

May I know if the PHY and MCU need to share a 50Mhz active crystal? The customer plans to use an external crystal to provide a clock source for both the PHY and MCU. 

Regards,

Ivy

Hi Ivy,

Please refer to section 8.4.6.2 of the datasheet for RMII implementation. 50Mhz oscillator can be shared between PHY and MCU. 50Mhz crystal cannot be used.

In RMII master mode, the PHY uses a 25Mhz crystal and can provide 50Mhz clock to MCU

Thanks,

David

Hi David,

Understood, thanks for your comments.

Could you please give some suggestions for another question? What are the specific parameters requirements of the clock buffer with DP83TC814S-Q1? Do you have a recommended GPN? 

Regards,

Ivy