Supercapacitors for Low Power Wireless Networks
Supercapacitors can be used to give you the extra power burst you need to support wireless sensor nodes operating from low power energy sources or energy harvesters. A low-power energy source such as a 3V watch battery or a solar, heat or vibration-energy-harvesting module can usually supply the average power required for a wireless system, but may not be able to provide the peak power to transmit data over wireless networks such as IEEE 802.15.4 (Zigbee), 802.11 (WLAN) or GSM/GPRS.
Zigbee transmission (peak power 10 – 100mA) will shorten a 3V button battery’s life, and require a larger battery than would be necessary to support the average load power. Even worse, a 3V battery cannot support a GSM or GPRS transmission (peak power 1 – 2A) at all without some additional source of power.
The CAP-XX BritePower solution resolves these issues with a single-cell, thin-form supercapacitor that stores energy generated at low power by the battery or from the environment, and then delivers it in high power bursts for data collection and transmission. The below paper outlines innovative power architectures, showing designers how to use a single-cell CAP-XX supercapacitor rated at 2.7V in conjunction with a 3V energy source, instead of a larger and costlier dual-cell supercapacitor rated at 3V or more. Using a single-cell supercapacitor also reduces the leakage current of the power solution, thereby increasing battery life and reducing energy losses from environmental harvesting modules.
The technical paper is available at http://www.cap-xx.com/news/news.htm#InTheNews
