SLVSF02D March 2019 – May 2020 TPS23881
Throughout this document the use of the terms port and channel will be used regularly, but these terms are not interchangeable. Instead the term port will be used to refer to the PSE PI (Power Interface), which is most commonly associated with a RJ45 connector, whereas the term channel will be used to refer to the individual power path or paths associated with each port.
Previous PSE devices commonly equated the number of controlled outputs as ports as each output would be dedicated to providing power on either the ALT-A or Alt-B pair set of a RJ45 jack/Ethernet port. However, with the adoption of 4-Pair power delivery sending power down both the ALT-A and ALT-B pair sets, there is now a need to differentiate between 2-pair and 4-pair capable PoE ports. Even more so, with the requirement to provide individual current limiting per pair set, any 4-pair port will now use two channels per 4-pair port to ensure safe and reliable delivery of power down each pair set.
As the TPS23881 is an 8-channel PSE controller. It can be configured to support up to eight 2-pair PoE ports or four 4-pair PoE ports, or any combination thereof where each 2-pair port accounts for one channel, and each 4-pair port accounts for 2 channels.