This reference design provides lightning surge protection solution for Power over Ethernet (PoE) Power Sourcing Equipment (PSE) systems based on TI's TPS23861 PSE controller. The need for implementing such protection will normally depend on the environment in which the PSE is intended to operate and the inherent isolation properties of the PSE. For industrial(NVR: DVR:etc) and Telecom(Ethernet switches: Gateways: etc) applications: lightning surge protection is an important design consideration in the system.