Dual power supply control LSI for solar and battery driven devices

March 12, 2012 // By Julien Happich
Lapis Semiconductor has developed the power controlling “ML9077/ML9078 series” LSIs for small sized electronics using dual power supplies like solar panel and batteries such as coin battery. These LSIs provide stable power supply to electronic components like microcontrollers by controlling the switching between the primary/secondary (rechargeable) batteries and solar panels as well as perform the charge control of power supplied from the solar panels to the secondary battery.

The ML9077 automatically controls the power supplied to the microcontroller and peripheral components from a rechargeable battery (VBAT) as well as from the solar panels to the rechargeable battery based on the remaining charge of the battery. Protection functions are built in, including charging stop with overcharge detection and malfunction prevention that prevents failures due to power supply stoppage caused by low voltage. Current consumption is less than 80nA (at 25°C). The ML9078-00 continuously monitors the voltage generated by the solar panel (VSC) and at the primary battery (VBAT) and selects the higher voltage for supply to the microcontroller and peripheral devices. It protects the primary battery by preventing the flow of generated current from the solar panel.

High voltage supply to the microcontroller is prevented by converting the generated voltage by the solar panel to low voltage. In addition, protection functions are built in such as power supply selection monitoring, reducing peripheral circuitry significantly. Current consumption is less than 80nA (at 25°C). For some products the current consumption is less than 150nA (at 25°C). The common characteristics of these LSIs is that they both control dual power sources of solar panel and battery on an entirely-independent basis. They come in a 3x3mm WQFN package.

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