College - Author 1

College of Engineering

Department - Author 1

Electrical Engineering Department

Degree Name - Author 1

BS in Electrical Engineering

College - Author 2

College of Engineering

Department - Author 2

Electrical Engineering Department

Degree - Author 2

BS in Electrical Engineering



Primary Advisor

Taufik, College of Engineering, Electrical Engineering Department


Offline power supplies are necessary for any sort of electronic device that utilizes wall power. For offline power supplies, it is a common practice to use the switching mode method where the high voltage AC input is first rectified and then switched at high frequency to a much lower voltage. This method has been known to be very efficient. Also, it’s more efficient than a linear supply method where the AC input is stepped down and then linearly regulated down to a low voltage. Despite the efficiency benefit, the switching method employs a high frequency transformer and inductor. This will make the design relatively costly and bulky (especially at a very low output power). This project will look into a new method of producing a low DC voltage from a high AC input voltage. The method utilizes a switch that prevents the power supply to charge a rectifier capacitor filter all the way up to the peak of the AC input voltage. Rather, the input is clamped at a much lower voltage that is closer to the output voltage such that a low dropout (LDO) regulator could be used; thus, avoiding the use of an inductor while maintaining the high efficiency. The proposed design was tested through LTSpice simulation and results demonstrated the functionality of the design in achieving the desired output voltage. The efficiency of the power supply with the proposed input clamping and LDO method was measured to be above 70% at full load. Construction of a prototype for the proposed design was planned but was not carried out due to the COVID-19 pandemic.