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Posted on February 27, 2009 by  & 

Freescale Semiconductor harvests energy from each solar cell

Freescale Semiconductor has developed advanced, ultra-low-voltage DC-to-DC converter technology that enables solar cell start-up and operating performance at levels as low as 0.32 volts, as well as operation down to 0.25 volts. Most ICs cannot start up at voltages less than the typical turn-on voltage of a transistor (approximately 0.7 volts) without external assistance. This limitation reduces system design options and increases the complexity of power conversion and energy recovery applications involving ultra-low voltages. The technology has a conversion efficiency of 82 percent for solar and up to 90 percent for other types of energy harvesting.
This new technology and can enable practical and cost-effective ways of developing a wide range of single-cell solar power systems and other energy-harvesting applications, such as thermoelectric and mechanical scavenging systems. Possible applications include solar-powered battery chargers, trickle chargers for automotive systems, chargers for cell phones and laptops, remote data acquisition and industrial HVAC systems, PV-based traffic signals, solar-powered home and commercial lighting products and self-powered wireless transponders.
Using a low-cost single solar cell, Freescale's power conversion technology is engineered to charge a Li-Ion battery cell at 100mA. Present charging systems require multiple solar cells in series, which drives up cost, reduces efficiency, and increases sensitivity to shading and cell mismatches. Freescale demonstrated their technology in February at the Applied Power Electronics Conference and Exposition in Washington DC.
"We see no IC solutions currently available approaching the ultra-low-voltage capability and power conversion efficiency of our analog technology demonstrated at APEC," said Arman Naghavi, vice president and general manager of Freescale's Analog, Mixed-Signal and Power Division. "Freescale has demonstrated a single-chip solution that addresses one of the most difficult technological and practical challenges of extracting power from a single solar cell. This breakthrough can be used to help reduce the cost and streamline the development of innovative solar chargers, energy-harvesting systems and other low-voltage energy sources."
Source: Freescale Semiconductor
Top Image: A single solar cell. (Source:

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Posted on: February 27, 2009

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