Thursday 7 January 2010

Harvesting power

A wide range of low-power industrial sensors and controllers are turning to alternative sources of energy as the primary or supplemental means of supplying power. (see Cables no-longer Required earlier this month). Ideally, such “harvested” energy will eliminate the need for wired power or batteries altogether. Transducers that create electricity from readily available physical sources such as temperature differentials (thermoelectric generators or thermopiles), mechanical vibration (piezoelectric or electromechanical devices) and light (photovoltaic devices) are becoming viable sources of power for many applications. Numerous wireless sensors, remote monitors, and other low power applications are on track to become near “zero” power (or nanopower) devices using only harvested energy only.

The New Direction:
Linear Technology continues to grow its family of energy harvesting power ICs to specifically address the emerging requirements of green power. The LTC3588-1 is the latest device in this growing family which can harvest electrical power from mechanical vibration. Its combination of an internal low-loss full-wave rectifier, high efficiency synchronous buck converter and nanoamp quiescent current make it ideal for energy harvesting applications which have an energy source such as a piezoelectric transducer. While the input capacitor continually charges via its internal rectifier, the LTC3588-1 requires only 950nA of quiescent current to regulate an output (at no load). Then, it can wake up and deliver up to 100mA of output current at 1.8V, 2.5V, 3.3V or 3.6V to drive a wide array of low power microprocessors, sensors and wireless RF links eliminating any need for external batteries or other power sources. The combination of a few externals and a tiny 3mm x 3mm DFN (or MSOP) package offer a very compact solution footprint for energy harvesting applications.

Key features of the LTC3588-1 include:
  • 950nA Input Quiescent Current (Output in Regulation – No Load)
  • 450nA Input Quiescent Current in UVLO
  • 2.7V to 20V Input Operating Range
  • Integrated Low-Loss Full-Wave Bridge Rectifier
  • Up to 100mA of Output Current
  • Selectable Output Voltages of 1.8V, 2.5V, 3.3V, 3.6V
  • High Efficiency Integrated Hysteretic Buck DC/DC
  • Input Protective Shunt – Up to 25mA Pull-Down at VIN ≥ 20V
  • Wide Input Undervoltage Lockout (UVLO) Range
  • Available in 10-Lead MSE and 3mm × 3mm DFN Packages

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