The Power Board of the KM3NeT Digital Optical Module: design, upgrade, and production

The KM3NeT Collaboration is building an underwater neutrino observatory atthe bottom of the Mediterranean Sea consisting of two neutrino telescopes, bothcomposed of a three-dimensional array of light detectors, known as digitaloptical modules. Each digital optical module contains a set of 31 three inchphotomultiplier tubes distributed over the surface of a 0.44 m diameterpressure-resistant glass sphere. The module includes also calibrationinstruments and electronics for power, readout and data acquisition. The powerboard was developed to supply power to all the elements of the digital opticalmodule. The design of the power board began in 2013, and several prototypeswere produced and tested. After an exhaustive validation process in variouslaboratories within the KM3NeT Collaboration, a mass production batch began,resulting in the construction of over 1200 power boards so far. These boardswere integrated in the digital optical modules that have already been producedand deployed, 828 until October 2023. In 2017, an upgrade of the power board,to increase reliability and efficiency, was initiated. After the validation ofa pre-production series, a production batch of 800 upgraded boards is currentlyunderway. This paper describes the design, architecture, upgrade, validation,and production of the power board, including the reliability studies and testsconducted to ensure the safe operation at the bottom of the Mediterranean Seathroughout the observatory's lifespan