How the charger works

Chargers are an indispensable part of modern electronic devices and are used to provide charging functions to various batteries. This article will introduce the basic working principle of the charger and its schematic diagram in detail, to help readers understand its internal structure and operation.

First, the basic principle of the charger

The main function of the charger is to convert alternating current (AC) to direct current (DC) in order to charge the battery. This process involves multiple steps, including rectification, filtering, regulation, and charge control. The basic components of the charger include: AC power supply, rectifier circuit, filter circuit, control circuit, output circuit and protection circuit.

Second, the schematic diagram analysis of the charger

Let's take a look at a typical charger schematic to break down its components and functions in detail.

A. AC power input

The charger is connected to the mains grid via a mains plug, typically 220V AC.

B. Rectifier circuit

After the alternating current enters the charger, it first passes through the rectifier circuit. The rectifier circuit is usually composed of a bridge rectifier stack (D1~D4) composed of four diodes, and its function is to convert alternating current into pulsating direct current.

C. Filter circuit

The rectified pulsating DC contains a large amount of AC components, which needs to be smoothed by a filter circuit. The filter circuit is mainly composed of large-capacity electrolytic capacitors (C1, C2), which can filter out the AC component in the pulsating DC current and obtain a relatively smooth DC voltage.

D. Control circuit

The control circuit is the core part of the charger, which is responsible for regulating the output voltage and current to ensure that the battery is charged safely. The control circuit typically includes a pulse-width modulation (PWM) controller, such as the UC3842 chip. The UC3842 regulates the output voltage and current by controlling the on-time of the switch by adjusting the width of it