With the development of the times now, the cell phone has become a necessary item for everyone, but also to facilitate communication between people, and the phone can only work properly if it is charged, so what is the principle diagram of the cell phone charger? Here is a description to see how the charger is to charge the phone.


First, the low frequency (50Hz) AC rectification for DC, and then use the field effect tube (equivalent to a rotating switch switch) to switch this DC into a high frequency (tens of KHz) AC signal, and then through the transformer transformer, and then rectified into DC. The purpose of this is to reduce the size of the magnetic element, i.e., the transformer.


220 AC rectifier, then use the oscillation circuit to start (most are self-excited), become a few tens of kilohertz high-frequency signal, and then through the isolation of the high-frequency transformer transformer into a few volts of low-voltage high-frequency, filtering, voltage regulation and then output 5-6 volts of DC (according to the phone points) to charge the phone. Similar to a small switching power supply, compared to the frequency transformer (very heavy kind of iron core transformer) high efficiency, light weight.

Nowadays, cell phone chargers mostly use lithium-ion batteries, speaking of this lithium-ion battery, first of all, a brief introduction, the so-called lithium-ion battery is the use of carbon materials capable of absorbing and detaching lithium ions as the anode active material of the battery, lithium ion symbol for Li-ion. batteries are generally composed of positive electrode, negative electrode, diaphragm, electrolyte and other basic elements.

Lithium-ion battery charging process is divided into two steps: first, constant current charging, its current is constant, the voltage is rising, when the voltage is charged to 4.2V automatically switch to constant voltage charging, constant voltage charging when the voltage is constant, the current is getting smaller and smaller until the charging current is less than the pre-set value, so some people use the direct charge to charge the cell phone battery when it is clear that the power display has been full, but still In fact, the voltage at this time has reached 4.2V, so the power display is full, then it is in the process of constant voltage charging.


Why constant voltage charging it, directly charge with constant current to 4.2V is not on the line, in fact, it is easy to explain, because each battery has a certain internal resistance, when charging with constant current to 4.2V, the 4.2V is not the actual battery voltage, but the battery voltage plus the sum of the voltage consumed on the internal resistance of the battery, if the current is very large, then the voltage consumed on the internal resistance is also If the current is large, then the voltage consumed on the internal resistance is also very large, so that is the actual battery voltage may be much smaller than 4.2V, so to use the constant voltage charging process, the charging current slowly down, so that the actual battery voltage is very close to 4.2V.


When charging a cell phone, the charger first turns 220V AC into high-voltage DC through a rectifier circuit, then into a high-frequency high-voltage pulse through a switching tube, and later into a low-voltage pulse through a transformer, with the specific value of the low-voltage depending on the voltage needed by the device being charged. Finally, the low-voltage pulse passes through the rectification and voltage regulator circuit and becomes the corresponding DC power. In other words, the process from 220V AC to 5V DC will mainly go through rectification circuits, transformers, voltage regulator circuits, etc. The charger just changes the form of electrical energy.


The charger is using high frequency power supply technology, using advanced intelligent dynamic adjustment charging technology. Industrial frequency machine is designed with the traditional analog circuit principle, the machine internal power devices (such as transformers, inductors, capacitors, etc.) are relatively large, there is generally less noise when running with a larger load, but the model in the harsh grid environmental conditions resistance performance is stronger, reliability and stability are stronger than the high-frequency machine.


Through the above introduction we understand the cell phone charger schematic diagram of the relevant content, only to understand the principle of cell phone charger, in order to charge scientifically and reasonably, not to damage the phone.