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EETASIA.com — While the infrastructure for plugging portable devices into the USB for datacom-with-power applications is fairly universal today, using the USB as a power source for direct powering or charging a battery isn’t necessarily foolproof. You’ll generally need over-voltage protection (OVP) circuitry; here’s what to consider in designing your discrete or IC-based circuit.

Downstream systems that you want to connect to can be powered in several ways. In the typical setup, PCs and peripheral devices plug into a connector that has a Vbus supply pin and D+ and D- data pins. The user should expect to see a Vbus voltage, as defined by the USB spec, of nominally 5V (maximum 5.25V). The Vbus pin is usually connected to the supply input pin of a transceiver (sometimes through a low dropout regulator, which has a maximum rating of 6V) and/or the input pin of a charger when the Vbus supply is used for charging a Li-ion battery (maximum rating is 7- to 10V in most cases).

View the PDF document for more information.

Adapted from EETASIA.com

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