Energy Harvesting Reference Design
Intersil Corporation and Nextreme Thermal Solutions, an innovative leader in cooling and energy harvesting solutions, have developed a reference design for a self-powered, wireless strain gauge module using precision amplifiers and switches from Intersil. Powered by thin-film thermoelectric technology, the gauge measures strain in locations that are not easily accessible, such as inside walls, in pipes, or under bridges, then transmits the measurements to a remote, easily accessible receiver.
The module consists of a strain gauge, an Intersil ISL28133 chopper amplifier, an Intersil ISL54051 low on-resistance switch, and an Si1012 wireless module. A 100µA continuous current draw is sustained by the Nextreme TherMobility thermal energy-harvesting unit, and excess energy is stored in a capacitor until required. Once the module is installed, it will operate untouched throughout its lifetime.
The new reference design will be demonstrated at the Nextreme booth at the Energy Harvesting & Storage USA conference in Boston on November 15 and 16. The reference design and more information about the components used are available from Intersil Corporation’s website at http://www.intersil.com/energyharvesting/.
The Intersil-Nextreme collaboration represents the first step in a joint program of wireless sensor network development for energy harvesting and ultra-low power systems.
Chopper Amps Feature Low Power, Low Voltage Offset Over Temperature
The Intersil ISL28133 chopper-stabilized op amp was chosen for this design because it is the lowest power op-amp of its type, requiring only 18µA during operation. Low power and low voltage offset over temperature (75nV/ºC) and time are key features for energy harvesting applications, and the ISL28133 is a proven performer in both of these areas. In addition, the small size (1.6mm x 1.6mm µTDFN package) of the ISL28133 and 1.8V supply voltage makes it an ideal choice to be paired with small, low powered sensors, which may need to be powered by energy harvesting devices. As an alternative design choice, Intersil also has a lower noise chopper stabilized op amp, the ISL28134, with a 15nV/ºC voltage offset drift over temperature.