Solar charger IC touts up to 95% efficiency

STMicroelectronics has released a battery charging IC that aims to increase charging efficiency using the sun's radiated energy. This will enable longer mobile equipment runtime and avoid an unexpected power outage when there is no mains connection available.

With the battery charging IC, solar energy will be a valuable source of free energy that can be used in portable consumer, healthcare and security devices.

ST's SPV1040 is a step-up DC/DC converter tailored to be used as solar battery charger for portable applications to employ Maximum Power Point Tracking (MPPT), a technique for collecting the maximum possible energy from solar cells. It can be connected to strips of even just a few cells, allowing use in products such as portable healthcare devices, watches, calculators, wireless headsets, toys, or mobile phones. The battery charger and MPPT technology can also be used in equipment such as sensors and security cameras.

According to ST, the MPPT algorithm embedded in the SPV1040 dynamically adjusts the charger's input impedance to ensure perfect matching with the solar cell, thereby maximizing energy transfer to the battery and improving overall system efficiency. Without MPPT, changes in the solar cells caused by temperature, aging, dirt or unit-to-unit variation can produce mismatches that reduce the energy harvested, ST said.

The SPV1040 features input-voltage range of 0.3–5.5V and integrated low-loss synchronous rectifier and power switch. It offers up to 95 percent efficiency and has a shutdown pin to aid system-level power management. The SPV1040 also includes thermal shutdown and protection circuitry to improve battery and overall system safety.

Available in the TSSOP8 plastic package, the SPV1040 is in full production, priced at approximately $2.00 in quantities of 1000 units. Alternative pricing options are available for larger quantity orders. Evaluation boards and technical documentation are also available.