Charger

The devices we commonly refer to as chargers are technically power supplies. A power supply determines the voltage it provides and outputs it accordingly. The power supply sets the maximum current it can deliver. For example, PC USB ports can supply varying maximum currents depending on the type, such as 500mA, 900mA, 1.5A, or 3A.

However, the device receiving the current does not always require the maximum current. The receiving device controls the current flow, opening and closing a switch to regulate it.

A charger is a device and circuit that controls the voltage and current going into a battery. It is typically found inside devices like smartphones and portable gadgets that have batteries, which is why it is called a Built-In Charger.

A Built-In Charger adjusts the actual amount of current going into the battery during charging. When charging is needed, it opens the switch to allow current flow; when charging is complete, it closes the switch to stop the current supply.