This paper presents a functional design and modeling of smart conditioning circuit of a vibrational energy harvester based on electrostatic transducer. Two original features are added to the basic configuration previously published (whose model we presented on BMAS2007 conference). Firstly, we developed an auto-calibration block which allows the new harvester to adapt dynamically to the varying environment parameters (e.g., amplitude of external vibrations). Secondly, we propose an original schematic configuration based on dual output DC-DC converter, which implements a smart power interface with the load, allowing the harvester to manage a possibly variable load and adapt to different situations (e.g. unsufficient generated power level, load too large, etc.). The scheme of the power interface re-uses the coil existing in the basic harvester configuration. The new harvester architecture contains ldquosoftwarerdquo blocks which can be programmed to implement different power-management and auto-calibration strategies. We describe one possible algorithm of the whole architecture operation, and present the corresponding modeling results. The system is implemented as a mixed VHDL-AMS/ELDO model.