DESIGN CONCEPT AND CHARACTERISTICS OF A POWER-SUPPLY FOR OPTICAL NETWORK UNITS IN FTTH SYSTEMS

This paper describes the design concept and characteristics of a power supply for optical network units in Fiber To The Home (FTTH) systems. Powering architectures of local powering, network powering and power hub powering are compared in terms of cost and maintainability. A loca l powering architecture is selected for an ONU power supply because it is the most cost-effective overall compared with the others. The loca l power supply is mainly composed of a rectifier, DC-DC converters, a ringer, and batteries. A battery deterioration test function is import ant for the local power supply because battery lifetime varies dependi ng on ambient temperature, discharge history, and charging conditions, and it is shorter than other electrical components used in ONU. Suppl ying power using alternative batteries is also necessary because the c apacity of batteries installed in the power supply is limited. These f unctions and electrical characteristics are checked using an experimen tal power supply with Ni-Cd batteries.