What is the working principle of the mobile phone charger?

The mobile phone charger, literally understood, is a product that charges the mobile phone, but the mobile phone charger not only charges the mobile phone, but also charges the iPad, the camera, etc., so the role of the mobile phone charger is still very large. But many people are not sure what the mobile phone charger works like:

All mobile phone chargers are actually composed of a stable power supply (mainly regulated power supply, providing stable operating voltage and sufficient current) and necessary constant current, voltage limiting, time-limited and other control circuits.
Let’s take a look at the working principle of the mobile phone charger:

220V AC input, one end is rectified by a half wave, and the other end is stringed with a resistor and then filtered by capacitor. This 10 ohm resistor is used for protection. If an overcurrent occurs due to a fault in the back, the resistor will be blown to avoid causing a larger fault. The right 4007, 4700pF capacitor and 82KΩ resistor form a high-voltage snubber circuit. When the switch tube 13003 is turned off, it is responsible for absorbing the induced voltage on the coil, thereby preventing high voltage from being applied to the switch tube 13003 and causing breakdown.

13003 is a switch tube used to control the on and off between the primary winding and the power supply. When the primary winding is continuously turned on and off, a varying magnetic field is formed in the switching transformer, thereby generating an induced voltage in the secondary winding. The 510KΩ at the left end is the starting resistor, which provides the base current for starting the switch. The 10Ω resistor below 13003 is the current sampling resistor. The current is sampled and becomes a voltage (the value is 10*I). This voltage is applied to the base of transistor C945 via diode 4148.

When the sampling voltage is greater than 1.4V, that is, when the switching tube current is greater than 0.14A, the transistor C945 is turned on, thereby lowering the base voltage of the switching tube 13003, thereby reducing the collector current, thus limiting the current of the switch and preventing The current is too large and burned. The induced voltage of the winding (sampling winding) at the lower left of the transformer is rectified by a rectifying diode 4148, and the 22uF capacitor is filtered to form a sampling voltage. After the sampling voltage passes through the 6.2V Zener diode, it is applied to the base of the switch tube 13003 to realize the function of the regulated output.

FOCUSES is an innovative and energetic enterprise with the integration of the designing, manufacturing, selling of the Mobile Phone Wall Charger, Car Charger, Power Bank, iOS USB Data Cables and Tempered Glass Screen Protectors. Founded in the year of 2006, its headquarters is located in Shenzhen, China. Online Shop please visit https://www.focusesmall.com