Build a UPS for USB devices


Posted on Dec 29, 2012

Portable systems often include circuitry that derives power from an external source, such as USB. When the system disconnects from the USB supply, a battery takes over and supplies current via a dc/dc converter. A diode-OR connection (Figure 1 offers the easiest way to ensure that the supply voltage doesn`t sag during this switchover to the battery.






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