The phenomenon of Universal Serial Bus (USB) devices ceasing their connection to a portable computer upon the system entering sleep mode is a common occurrence. This typically manifests as a USB-connected mouse or keyboard becoming unresponsive, or an external storage device appearing to disconnect when the laptop transitions to a low-power state. For example, data transfer to an external hard drive might be interrupted, or a USB-connected printer will become unavailable when the laptop is in sleep mode.
The management of power to USB ports during sleep is a crucial element of modern laptop energy efficiency. Historically, continuous power delivery to all peripherals was the standard. However, the desire to extend battery life has led to the implementation of power-saving measures that involve selectively disabling power to USB ports when the system is idle. This design choice prioritizes energy conservation but can lead to user frustration when active USB connections are unexpectedly terminated.
