Power USB devices from a vehicle
Automotive accessories such as PNDs (portable navigation devices) usually receive their power or charge using a simple adapter that a user plugs into a cigarette lighter. Sometimes, however, you may want to power or charge two devices at once. The circuit in Figure 1 can handle that task.
IC1 generates 5V from any 7.5 to 76V input—a wide enough range to include the complete range of car-battery voltage plus the 40V spike that can occur during a load dump. The IC is simple to use because it has an internal power switch and requires no compensation circuit.
Power USB devices from a vehicle – [Link]
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