Ricoh Electronic Devices Co., Ltd. in Japan has launched the R1800 Buck DC/DC Converter, designed for use in energy harvesting devices which are able to collect and store energy obtained from sources such as solar or vibration energy. Target applications include wearables for sports and healthcare, wireless sensors and IoT devices.
This is a DC/DC converter collecting energy generated from a photovoltaic or vibration energy harvester cell and stores it in a super capacitor or rechargeable battery. An ultra-low quiescent current of 144 nA even allows to use the harvester circuit in a low-illumination environment and when the generated level of energy is moderate. The R1800 enables the development of batteryless applications, which neither need battery replacement maintenance nor need power from mains to recharge. Instead, the application will operate as long there is sufficient light or vibration available.
As soon as there is sufficient energy available on the input side, the buck DC/DC Converter will be enabled to transfer energy from input to output. During this phase the transferred energy is stored in a super capacitor or battery on the output until the energy left on the input drops below a threshold. The DC/DC Converter is disabled and new energy will be collected on the input. This process repeats and increases the energy level in the capacitor or battery until the required output voltage is reached.
A reverse current protection circuit prevents that a current flow will occur from output to input as soon the energy harvesting cell does not provide energy, the circuit is triggered when the input voltage drops below the output voltage. The R1800 is available in a DFN(PLP)2730-12 package.