PCB implementation of a lithium-ion capacitor charge-discharge protection circuit.

Abstract

Lithium Ion Capacitors have found application in Automated Weather Stations. They are a relatively new technology, there is currently no analogue all-in-one charge-protection circuit design to prevent over charge/discharge. Therefore, this project’s main objective was to design and implement a charge-protection circuit to regulate the voltage within the range of 2.2V – 3.8V. The methodology was divided into four phases which include; Planning of the project, design and simulation of the hardware, fabrication of the hardware and PCB fabrication. The key results were that below 2.2V the LIC charged and the load was shut down, in between 2.2V to 3.8V the LIC charged and above 3.8V the LIC stopped charging. It is recommended to use high-fidelity comparators which give exact values at a given threshold unlike the general purpose comparators that were used for this project. Finally, a device which ensures that the LIC charges below 2.2V, between 2.2V to 3.8V and stops charging above 3.8V thus safe operation of the LIC was designed. A Printed Circuit Board (PCB) was also designed.