01-14-2019 07:23 PM
Please find the below comment per your two questions.
1. The MDC, MDIO pins are 3.3V tolerant.
2. I believe you are refer to our application note "CAP-AN102-R" for the backplane design. Please follow the [Backplane Connection/Termination] Figure you attached and follow the [Table1: Termination Bias Requirements] Device BCM53262/M/S.