General
Review and verify the following for the custom schematic design:
- The sections above, including relevant
application notes and FAQ links.
- Pin attributes and signal description.
- Electrical characteristics, timing parameters, and any additional available information.
- MAC interface configuration and recommended connections including series resistors (on the TDn signals near to processor MAC TDn output pins and optional 0Ω series resistors near the attached device for the RDn signals).
- IO level compatibility between processor MAC and EPHY (attached device). The attached device IO supply and IO supply for GENERAL0 IO group VDDS0 referenced by the interface signals are recommended to be connected to the same supply source.
- Matching of processor and EPHY clock specifications.
- Clocking of EPHY and processor MAC including addition of buffers based on the EPHY configuration and clock architecture (use of common Oscillator and Buffer or RMII interface). When the clock output connects to more than one inputs, each of the clock inputs are required to be buffered using individual buffers.
- Interface connections, IO level compatibility, fail-safe operation (when MACs are powered by different power sources) and matching of clock specifications when MAC-to-MAC interface is used.
- MDIO interface connection including pullup for MDIO data added near to the EPHY. MDIO connection to multiple devices and the addition of pullup near each EPHY.
- When 2 EPHYs are used, configuration of EPHY device address to read the internal registers through the MDIO interface.
- Implementation of EPHY reset logic. When 2 EPHYs are used, the recommendation is to provide provision to reset the EPHYs individually.
Schematic Review
Follow the below list for the custom schematic design:
- Provision for series resistor for the processor MAC transmit signals TDn near to the processor output pins have been provided and the initial value (0Ω or 22Ω).
- Verify the EPHY reset implementation including ANDing logic, EPHY reset input pull and compare with EVM as required.
- Verify EPHY device address configuration when two EPHYs are used and MDIO interface is required
- MDIO data pullup is provided near to the EPHY.
- Verify the IO level compatibility - the attached device IO supply and IO supply for IO group referenced by the processor interface signals are connected to the same supply source.
- Compare the bulk and decoupling capacitors used for all the EPHY supply rails with EVM schematics when TI EPHY is used.
- Pullup is provided for processor GPIO input of the EPHY reset ANDing logic.
- Pullup on the MDIO clock can be optional (EPHY can have internal pulldown; verify in the data sheet).
- Supply rails connected follow the ROC.
- When more than 1 EPHY is connected, provision to reset the EPHYs individually is provided. Addition of pull at the EPHY reset input as required.
Additional
- Follow the steps below when TI EPHY is used:
- Obtain a review of the
implementation done with the EPHY business unit or product line
- Verify the power sequence
requirements for two-supply configuration and three-supply
configuration
- Verify the RBIAS resistor
tolerance as per the EPHY data sheet
- Selection of the RJ45
connector with integrated magnetics, follow EVM
- Provision for external
ESD protection for the MDI signals
- Connection of RJ45
connector shield to circuit ground
- The recommended bulk and
decoupling capacitors are provided (refer EVM as required)
- Use one output, individual buffer device, or dual or multiple output buffer to connect the clock output of the oscillator to the processor and EPHYs. For specific use case (requirement for some of the industrial applications using a Time Sensitive Networking (TSN)) input and two or more output (based on number of EPHYs used) buffer is recommended for the processor and the EPHYs.
- When EPHY is configured as RMII slave (peripheral), two-output phase aligned buffer with a common input is recommended.
- If space is not a constraint, consider adding 0Ω series resistors on the RDn signals near to the EPHY.
- ANDing logic additionally performs IO level translation. Verify the reset IO level compatibility before optimizing the reset ANDing logic. IO level mismatch can cause supply leakage and affect processor operation.
- Verify recommendations as per the data sheet or EVM implementation are considered for the attached device, including terminations and external ESD protection.