8.3.4.3 System Level Components (not shown in the schematic diagrams)
TVS: The system TVS should have a minimum reverse standoff voltage of 58 V and a maximum clamping voltage of 95 V at the expected peak-surge current.
Bulk Capacitor: The system bulk capacitor(s) should be rated for 100 V and can be an aluminum electrolytic type. Lower values can be paralleled to achieve at least 47 µF per four ports.
Digital I/O Pull-Up Resistors:RESET, AIN, A3, and SHTDWN are internally pulled up to VDD with a 50-kΩ (typical) resistor. A stronger pull-up resistor can be added externally such as a 10 kΩ, 1%, 0.063 W type in a SMT package. SCL, SDAI, SDAO, and INT require external pull-up resistors within a range of 1 kΩ to 10 kΩ depending on the total number of devices on the bus. The AOUT pin is either connected to an upstream device (to the AIN pin) or left unconnected and as such requires no external pull-up resistor.
Ethernet Data Transformer (per port): The Ethernet data transformer must be rated to operate within the IEEE802.3at standard in the presence of the DC port current conditions. The transformer is also chosen to be compatible with the Ethernet PHY. The transformer may also be integrated into the RJ45 connector and cable terminations.
RJ45 Connector (per port): The majority of the RJ45 connector requirements are mechanical in nature and include tab orientation, housing type (shielded or unshielded), or highly integrated. An integrated RJ45 consists of the Ethernet data transformer and cable terminations at a minimum. The integrated type may also contain the port TVS and common mode EMI filtering.
Cable Terminations (per port): The cable terminations typically consist of series resistor (usually 75 Ω) and capacitor (usually 10 nF) circuits from each data transformer center tap to a common node which is then bypassed to a chassis ground (or system earth ground) with a high-voltage capacitor (usually 1000 pF to 4700 pF at 2 kV).