Design Of A 120W Adaptor Applicable To Laptop

As the development of the laptop, it is necessary to develop next generation of adaptor for the laptop. This paper reviews the development of the adaptors, and points out some design issues. In order to meet the requirement of the next generation of adaptor, this paper proposed a two-stage approach, which consists a power factor correction (PFC) stage and a dc/dc stage. The PFC stage is a Boost converter operating in discontinuous current mode (DCM) boundary to achieve high power factor and avoid reverse recovery of the Boost diode. The dc/dc stage consists two interleaved Flyback converters to reduce the input current and output current, and as a result, the output capacitor can be reduced. In order to increase the efficiency of the PFC stage at low line, its output voltage is controlled to be various from 210V to 390V linearly with the line voltage. Synchronous rectifier is adopted to the Flyback converter to increase its efficiency. This paper presents the operation principle and derives the key expressions of the proposed two-stage approach along with the SR. Adopting the proposed two-stage approach, a 120W adaptor with universal input and 19V/6.3A output is designed, and a prototype is built in our lab. The experimental results verify the effectiveness of the proposed approach.