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Charging docks supply power and do not include a host device or data pins, allowing any capable USB device to charge or operate from a standard USB cable. Charging cables provide power connections, but not data. In a charge-only cable, the data wires are shorted at the device end, otherwise, the device may reject the charger as unsuitable.
Some devices operate in different modes depending on whether the data connection is made. Charging docks supply power, and do not include a host device or data pins, allowing any capable USB device to charge or operate from a standard USB cable. Charging cables provide power connections but not data. In a charge-only cable, the data wires are ...
USB signals are transmitted using differential signaling on a twisted-pair data cable with 90 Ω ± 15% characteristic impedance. [6] Low speed (LS) and Full speed (FS) modes use a single data pair, labelled D+ and D−, in half-duplex. Transmitted signal levels are 0.0–0.3 V for logical low, and 2.8–3.6 V for logical high level.
USB On-The-Go (USB OTG or just OTG) is a specification first used in late 2001 that allows USB devices, such as tablets or smartphones, to also act as a host, allowing other USB devices, such as USB flash drives, digital cameras, mouse or keyboards, to be attached to them. Use of USB OTG allows devices to switch back and forth between the roles ...
A common EPS must include a cable with a micro USB-B (2.0) connector for connecting to a mobile phone. This cable can be either captive (permanently attached to the power supply) or detachable. If detachable, the cable must connect to the power supply via a standard USB type-A plug. [12]
Quick Charge is a proprietary technology that can charge battery-powered devices, primarily mobile phones, at power levels exceeding the 7.5 watts (5 volts at 1.5 amps) supported by the USB BC 1.2 standard, using existing USB cables. The higher voltage available allows more power (watts) to be supplied through wires without excessive heating.
Juice jacking is not possible if a device is charged via a trusted AC adapter or battery backup device, or if using a USB cable with only power wires. For USB cables with data wires, a USB data blocker (sometimes called a USB condom) [25] can be connected between device and charging port to disallow a data connection. [26]
The USB interface is vulnerable to security exploits such as BadUSB that abuse the combination of USB's ability to connect many different kinds of devices, its inability to verify that devices are actually what they claim to be, the possibility for USB devices to change their type or announce additional subdevices while plugged in, and its ...