The TMI7608 is an 8-port PSE (Power Sourcing  Equipment) controller IC for PoE (Power over  Ethernet) systems. It integrates power, analog and  logic circuits into a single chip, and can be used for  Midspan and Endpoint PSE applications. TMI7608 meets IEEE 802.3af 2003 requirements,  such as multi-point resistor detection, PD  classification, DC Disconnect, and back-off for  midspan. It also meets all IEEE 802.3at 2009  requirements, such as two-event classification and  supply maximum 36W per port. The device also  supports class 5 for detection and classification of  high-power PDs. The device supports singlesupply operation, provides up to 50W to each port  (class 5 enabled). The 3.3V regulator is built-in to support external  devices. Multiple TMI7608 can integrate to build an  8xN ports PSE system, and I2C bus uses to collect  PD power status from each TMI7608 to support  global power managements. Management switch host has options to communicate TMI7608 via I2C bus for PSE management activities. Opto-couplers can be implemented to provide electrical isolation between the host and TMI7608 for signal communication.