First, the type of power adapter
Power adapter is mainly divided into two kinds, linear power supply and switching power supply.
1, linear power source is AC power through transformer, rectifier circuit rectifier DC voltage is not stable, the power adapter to achieve high precision DC voltage, must pass through the adjustment of the output voltage voltage feedback circuit. Advantages: the power supply technology is mature, the circuit is simple, and no switching power supply has interference and noise. Disadvantages: voltage feedback circuit is working in a linear state, the adjustment of the tube power consumption, low conversion efficiency, the use of inductive transformer, so the weight of the equipment is large.
2, switching power supply is the use of modern electronic technology, the control switch turn-on and turn off time ratio, maintain a stable output voltage power supplies, switching power supply adapter from the general pulse width modulation (PWM) control IC and MOSFET which has the advantages of high efficiency, small volume, can work in a wide range of voltage in. Disadvantages: interference to the power circuit is large, it is difficult to overhaul when the fault occurs.
Two, be sure that the power adapter is the transformer and rectifier.
The adapter is transformer, we should all know, through the exchange of 220V transformer, the rectifier DC, here is the consumption, and consumption of these will be transformed into heat, so the power adapter will heat is normal. Transformer is made of silicon steel sheet, the transformer is energized, resulting in magnetic flux, magnetic flux will lead to silicon steel between the role of force, resulting in buzzing sound, which is normal. But too much noise is not normal, there are many reasons:
1, AC voltage instability.
2, chip damage.
3, turn to turn short circuit.
4. Component damage.
Three, the application of power adapter
In the consumer electronics products are widely used, the output power is mostly within 100 watts, the rapid growth of market demand. Such as electric bicycle battery charger, small size LCD TV, laptop, printer, DVD player and set-top box and so on. Most of the early power adapter with linear transformer, with consumer electronic products with high efficiency, the power adapter with wide input voltage range, and the increase of copper, iron and manpower cost, this kind of power adapter inside the original linear transformer was gradually replaced most of the switching power supply.
Thus, according to the advantages and disadvantages of the two can be distinguished, mainly depends on the volume, weight, output voltage range. Transformer type, through coil step-down, after class rectifier, voltage regulator, larger size, stable performance, disadvantages, transformer cost is high, easy to heat. Switch type small size, low cost, but the quality of components is not good, it is easy to damage.