RGMII Voltage Levels
Added by Lucas Uecker about 2 years ago
I'm trying to determine if a alternate Ethernet PHY is okay to use with the RGMII interface of the SOM module. PHY controllers such as the LAN8670 and KSZ8041 tout their single 3.3v supply, so I'm assuming that's the voltage level they use on their MII lines. If I'm reading correctly, the RGMII on the SOM module is on voltage domain 7B which is internally set at 1.8V. Would these PHY controllers be safe to use with the SOM module?
Datasheets:
https://ww1.microchip.com/downloads/en/DeviceDoc/PB-LAN8670-1-2-60001536E.pdf
https://ww1.microchip.com/downloads/en/DeviceDoc/00002245B.pdf
Replies (1)
RE: RGMII Voltage Levels - Added by Daniel Vincelette about 2 years ago
Hi Lucas,
You are correct the RGMII interface on the SOM is hardset to 1.8V, which wouldn't be able to interface with a 3.3V PHY. In order to interface to a 3.3V level ethernet PHY you need to route one of the HPS ethernet MACs through the FPGA fabric and out to a bank that is set to 3.3V.
Dan
