Charge battery via USB

The USB interface specification indicates that the interface can power the device. With the transformation from parallel port to serial port, various devices have undergone dramatic changes and can be easily connected to the PC.

In addition to directly powering USB devices, one of the most useful functions of USB power supplies is charging batteries. Many portable devices, such as MP3 players, PDAs, etc., need to exchange data with a PC. If the same cable can be used to charge the battery while exchanging data with the PC, it will greatly facilitate the use of the device. Combining USB functionality with battery charging allows a wide range of devices to be cord-free, such as removable network cameras, that work whether they are connected to a PC or not. In many cases, those clunky AC adapters you once used are no longer needed.

USB battery charging can be complex or simple, depending on the requirements of the USB device. Factors that influence design include more than the usual cost, size, weight, etc. Other important factors include: 1) how quickly a device with a depleted battery is required to become fully functional when plugged into a USB port; 2) how long the battery is allowed to charge; 3) power distribution within USB power limits; 4) whether it is required An AC adapter charges. These issues and corresponding solutions will be studied after discussing USB power issues.