Design of a battery-operated portable DC power supply. Part 2 : output current monitoring and protection

• Main Author: Tan, Huan You
• Other Authors: Chen Tupei
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/74823
• Institution: Nanyang Technological University

Imagine a power supply without overcurrent protection. When there is an overload condition, the power supply as well as the load may be damaged, and an undesirable result would be to pose a threat to the safety of the user. Incorporating an overcurrent protection circuit increases the reliability of the power supply and as a result, protects the safety of the user. In recent years, the application of portable low-power electronic products in consumer, communications and computer electronics is increasing. This has give rise to a high demand for portable DC power supply. Traditionally, overcurrent protection for lowpower application is typically achieved by adding an inline fuse to the circuit. Inline fuse is a single-use device where replacement can be time-consuming. This project aimed to design a low-cost reusable overcurrent protection circuit which can cut off the DC power supply when the output current reaches 50 milliamperes; a guideline to ensure the safety of the user pertaining to direct current. The overcurrent protection circuit proposed in this paper integrates current monitoring with current shutdown. Output current of the DC power supply is monitored continuously and when it reaches the threshold limit, the power supply will be shut down. This paper presents the hardware and software used, as well as the details on the programming part. The results from this project can be used as a basis towards other sophisticated overcurrent protection schemes.