Design and development of the Power Supply Board within the Digital Optical Module in KM3NeT

KM3NeT is a deep-sea neutrino telescope of very large scale (several km3) to be deployed and operated in the Mediterranean Sea. Neutrino-induced charged particles are detected by measuring their Cherenkov light in sea-water, using Photomultiplier Tubes inside transparent, pressure resistant spherical enclosures. The aim is to instrument several km3 of sea volume with tens of thousands of optical sensors, connected to the shore through electro-optical cables up to 100km. The KM3NeT collaboration has successfully developed an optical sensor, the Digital Optical Module, by placing 31, 3-inch Photomultiplier Tubes in a 17-inch glass sphere along with the readout electronics. Each Digital Optical Module is supplied power through a high voltage (400VDC) line, converted to low voltage (12VDC) in a breakout box before entering the Digital Optical Module. The Power Converter Board, situated inside the Digital Optical Module, is used to produce seven voltage rails as required by the Digital Optical Module electronic modules. This paper summarizes the design considerations and implementation of the Power Converter Board and the results of the trial runs so far. Technology and Instrumentation in Particle Physics 2014, 2-6 June, 2014 Amsterdam, the Netherlands