This paper presents the study of a modern yo-yo having a centrifugal clutch allowing the free rolling. First, the mechanical parts of the yo-yo are measured, allowing us to determine analytically its velocity according to its height of fall. Then, we are more particularly interested in the centrifugal device constituted by springs and small masses. The physics of this toy is suitable for undergraduate students, illustrating the concepts of dynamics of rigid bodies and of potential energy. (Contains 1 table and 7 figures.)