Low-cost Circuit for Implementing Smooth Power Supply Transition

This paper is to investigate the possibility of providing a smooth DC power supply transition for electronic devices. The transition is meant from power outlet as the main supply to battery as a backup supply and vice versa. The important requirements during the power-source transition process are to provide supply that is constant, reliable and free from fluctuations. The power supply smooth transition is important especially in electronic devices that utilizing microcontroller and microprocessor. Unstable power transition might create power transients and hence leads to unsynchronized between the processor and other components. This paper explains a circuit design with low-cost and effective method for monitoring and maintaining power supply transition. The purpose of this circuit is to check continuously the level of main supply to a load with a backup supply that will turn on whenever the main supply drops below specified minimum voltage level. When the main supply has reached above the specific minimum level, the control circuit will shut the backup supply and resumes the main supply to the load. The design of this circuit shows that the transition process runs smoothly and eliminates the transients. Although the transition process shows a slight drop in term of voltage supply, the effect does not give significant problem to the target system. It is concluded that the prototype design of this circuit is acceptable and meets the objective of the design.