5V

5V refers to a potential difference of five volts and is a common nominal DC supply voltage in electronics. It serves as a standard power rail for many digital circuits and is often used to power or bias components such as microcontrollers, sensors, and logic devices. Historically, 5V was the main operating voltage for TTL logic and remained widely used even as newer devices moved to lower voltages, such as 3.3V or 1.8V.

Electrical characteristics and tolerances vary by source, but a typical regulated 5V supply aims to stay within a narrow range, for example around 4.75 to 5.25 V for many USB-based and consumer electronics applications. The available current depends on the power source, ranging from small current-draw devices to powerful adapters and computer power supplies capable of several amperes.

Common sources of 5V include USB ports, dedicated 5V power adapters, and voltage regulators within devices. USB ports provide 5V nominal, with USB 2.0 offering up to 500 mA and USB 3.x up to 900 mA; USB Power Delivery can negotiate higher voltages but retains 5V as a baseline option. 5V can also be generated from higher-voltage supplies using linear or switching regulators, or produced directly by battery packs and boost converters in portable devices.

In practical use, the 5V rail is a foundational reference for many components and interfaces. Designers must ensure proper regulation, protection, and compatibility with devices that may be 5V tolerant or require precise voltage levels.