This paper presents the integrated design of a tunable interface for wideband energy harvesting, the Short-Circuit Synchronous Electric Charges Extraction (SC-SECE). By tuning both the phase of the energy harvesting event, PhiS , and the angular duration of the short-circuit phase, DeltaPhi, this interface maximizes both the harvested energy while tuning the dynamics of the energy harvester. The proposed ASIC is self-powered, includes a cold start, and only consumes less than 1uW, which is a very small percentage of the harvested energy. It includes as well a low-power (24nw) gradient algorithm which controls the value of (PhiS,DeltaPhi) and tries to maximizes the harvested power for any vibration's frequency and amplitude.