What Is the Difference Between Self-Powered and Bus-Powered USB Devices?

Self-powered USB device - A device that takes all of its power from an external power supply

Bus-powered USB device - A device that takes all of its power from the host computer's USB interface.

Why High-Current Devices Require External Power

While all USB ports provide some amount of power for attached devices, the available power may not be enough for certain high-current devices such as USB hubs or external hard drives. Bus-powered devices can cause issues if they need more power than is available from the host machine, as each additional device attached to the host computer reduces the total available bus power. If the power runs out, any USB device attached to the computer may suddenly disconnect, which could result in permanent data loss for a USB storage device.

How to Use Devices with Included Power Adapters

Many devices that include power adapters, especially USB hubs, will function in either self-powered or bus-powered mode. If a device comes with a power adapter, it should stay connected at all times, otherwise the device may not function as designed.

Applicable To

USBC-11IN1E, USBC-10IN1E, USBC-9IN1E, USBC-7IN1E, USBC-7IN1, AD-6IN1, USBC-4IN1, USB3-HUB4A, USBC-HUB4A, AMS-5IN1E, USB4-HUB3A, TBT4-HUB3C, USBC-HUB7BC, USB3-HUB7C, USB3-HUB3ME