Apple Adapter Manufacturer

How cell phone chargers getting smaller

Careful friends will find that since the birth of cell phones, they have become thinner and lighter, and at the same time, the size of cell phone chargers has become smaller and smaller. So how is this technically possible?

The previous charger used a linear regulated power supply, which usually required a bulky transformer to step down the 220V voltage and then connect the transistor charging circuit. Since the operating frequency of this transformer is 50Hz, the transformer must have enough inductive reactance, which means a large volume. So the volume of the previous charger is mainly limited by the transformer, and the previous transistors and resistive devices are relatively large, which also accounts for the volume.

Nowadays, the charger adopts switching power supply technology, which can directly rectify 220V, and then cut off or turn on the rectified voltage at a certain frequency to get an approximate square wave signal, and finally use negative feedback and smooth filtering to get a stable low-voltage source, eliminating the bulky transformer, of course, the switching power supply will also have a transformer, but due to the switching frequency of the switching power supply is much higher than the 50Hz, so the Requirements of the transformer inductive impedance is small, the volume of the transformer can be made very small. Coupled with the current device are miniaturized, the circuit can also be made very small.

So, it is the use of switching power supply technology, eliminating the large volume transformer; the use of small devices to reduce the size of the circuit, the two factors play a role, the size of the charger is much smaller.