A Photovoltaic Power Management System using a Luminance-Controlled Oscillator for USN Applications

Abstract

This paper presents a power management system of the dye-sensitized solar cell (DSSC) for ubiquitous sensor network (USN) applications. The charge pump with a luminance-controlled oscillator regulates the load impedance of the DSSC to track the maximum power point (MPP) under various light intensities. The low drop-out regulator with a hysteresis comparator supplies intermittent power pulses that are wide enough for USN to communicate with a host transponder even under dim light conditions. With MPP tracking, approximately 50% more power is harvested over a wide range of light intensity. The power management system fabricated using 0.13 mu m CMOS technology works with DSSC to provide power pulses of 36 mu A. The duration of pulses is almost constant around 80 mu s (6.5 nJ/pulse), while the pulse spacing is inversely proportional to the light intensity.