Power adapters are mainly divided into these two, switching power supply and linear power supply.
1) switching power supply is the use of modern electronic technology, control the switching tube turn on and off time ratio, to maintain a stable output voltage of a power supply, power adapter switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET
Advantages: high efficiency, small size, and can work in a wide range of voltage.
Disadvantages: greater interference with the power supply circuitry, the failure of the repair is more difficult.
2) Linear power supply is the alternating current through the transformer transformer, rectifier circuit rectifier filter to get unstable DC voltage, power adapter to achieve high precision DC voltage, must be adjusted through the voltage feedback circuit output voltage.
Advantages: This power supply technology is mature, simple circuit, and no switching power supply has the interference and noise.
Disadvantages: the voltage feedback circuit is working in a linear state, the power consumption of the adjustment tube, low conversion efficiency, due to the use of inductive transformer so the weight of the equipment is large.