In general, energy sources for harvesting applications are not only low power -- they are at low voltages. Piezoelectric devices are the exception, but thermoelectric generators (TEGs), inductive coils, and photovoltaic cells tend to have output voltages that range below half a volt. Most electronic circuits, including power conversion circuits, require voltages in the 2+ voltage range. So before an application can convert and regulate harvested energy from TEGs, coils, and PVs it must first boost the voltage up, and as efficiently as possible: When youíre working with microwatts to begin with, you canít afford to throw much away in your boost conversion.
Advanced Linear Devices has introduced the EH4200 series of MicroPowerStep-up Low-Voltage Booster Modules to perform this step-up power conversion function. Two micropower step-up booster models ALD EH4205/4295, each with different source input impedance matching characteristics are currently available. The ALD EH4205 features a nominal input impedance of 50 ohms while the ALD EH4295 features an input impedance of 950 ohms: Lower power applications will use the higher impedance version while a higher power can use the power impedance version.
ALD MicroPower Step-up Low-Voltage Booster Modules are compatible and best suited for driving loads such as the ALD EH300/EH301/EH300A/EH301A Energy Harvesting Modules. The EH4205/4295 output can be directly connected to the input terminals of the Energy Harvesting Module using a standard two-wire cable. ALD booster modules can also be used, independently for trickle-charging batteries or super-caps, including situations where the energy generating input source is intermittent and not well controlled or regulated.
Both EH4205 and EH4295 are available for immediate delivery and can be ordered from DigiKey or Mouser Electronics. Small quantities are priced from $41.00 each. Evaluation kits and cable assemblies are also available.