Mobile phone chargers can be broadly categorized into travel chargers, desktop chargers, and maintenance chargers, with users typically encountering the first two. Travel chargers are the most commonly sold type on the market, and they come in various forms, including inexpensive egg-shaped mini travel chargers, typical desktop card-type chargers, and high-end desktop chargers with LCD displays.
All mobile phone chargers consist of a stable power supply (primarily a voltage regulator, providing a stable operating voltage and sufficient current) plus necessary constant current, voltage limiting, and time limiting control circuits. The output parameters marked on the original charger (referring to a wired charger), such as output 4.4V/1A, output 5.9V/400mA, etc., refer to the relevant parameters of the internal voltage regulator.
Chargers for commonly used lithium-ion (Li-ion) batteries in mobile phones use a constant current, voltage limiting charging system. The charging current is typically around C2-that is, using a two-hour charging rate. For example, a 500mAh battery might be charged at 250mA for approximately two hours to reach 4.2V before being charged at a constant voltage.
