DP83640: add external Oscillator in RMII mode

Hi Haiwen,

Does the customer want to use a dedicated external oscillator, or generate the clock from another device (PHY, MCU, ...)?

Also, is the device being used in RMII master or slave mode?

The oscillator should follow these datasheet specifications, depending on the frequency:

Please refer to this layout checklist for guidelines on clock source layout:

https://www.ti.com/lit/zip/snlr048

Thank you,

Evan

Hello,
We want to place a 25M oscillator outside of 83640,
Using the RMII connection method,
The Ethernet speed is fixed at 100Mbps,
The direction of the Ethernet reference clock is 83640 output and processor input,
Do you have a reference circuit diagram? Thank you.

Hi Zhang,

Here are the connections for DP83640 in RMII master mode:

RX_CLK pin provides 50M output to the MAC input RMII reference clock.

For strapping the device in RMII master mode, please confirm RX_DV and TXD_3 are pulled high.

Thank you,

Evan