Bus powered意思

"Bus powered" is a term used in the context of USB (Universal Serial Bus) devices, particularly external hard drives, USB hubs, and other peripherals that draw power from the USB bus to operate. In other words, "bus powered" means that the device receives the electrical power it needs to function from the USB port to which it is connected, without the need for an external power adapter or power supply.

Most modern USB ports can provide up to 5 volts at 500 milliamps (0.5 amps) of current, which is enough power to run many small USB devices. However, some devices, such as external hard drives with larger motors, may require more power than the standard USB port can provide. In these cases, the device may come with its own power adapter or may be advertised as "self-powered" or "powered" rather than "bus powered."

Bus-powered devices are convenient because they do not require an additional power source, making them more portable and easier to use with laptops and other devices that may not have sufficient power output to support a self-powered device. However, bus-powered devices may have limitations on their power consumption and may not be able to deliver the same performance as devices that are self-powered or powered by an external power supply.