A switching-based Li-ion battery charger without any additional compensation circuit is proposed. The proposed charger adopts a dual-current sensor and a current window control to ensure system stability in different charge modes: trickle current, constant current, and constant voltage. The proposed Li-ion battery charger has less chip area and a simpler structure to design than a conventional Li-ion battery charger with pulse width modulation. Simulation with a 1000µF capacitor as the battery equivalent, a 5V input, and a 1A charge current resulted in a charging time of 1.47ms and a 91% power efficiency.

In this paper, the effective Long Range (LoRa) based wireless sensor network is designed and implemented to provide the remote data sensing functions for the planned smart agricultural recycling rapid processing factory. The proposed wireless sensor network transmits the sensing data from various sensors, which measure the values of moisture, viscosity, pH, and electrical conductivity of agricultural organic wastes for the production and circulation of organic fertilizers. In the proposed wireless sensor network design, the LoRa transceiver module is used to provide data transmission functions at the sensor node, and the embedded platform by Raspberry Pi module is applied to support the gateway function. To design the cloud data server, the MySQL methodology is applied for the database management system with Apache software. The proposed wireless sensor network for data communication between the sensor node and the gateway supports a simple one-way data transmission scheme and three half-duplex two-way data communication schemes. By experiments, for the one-way data transmission scheme under the condition of sending one packet data every five seconds, the packet data loss rate approaches 0% when 1000 packet data is transmitted. For the proposed two-way data communication schemes, under the condition of sending one packet data every thirty seconds, the average packet data loss rates without and with the data-received confirmation at the gateway side can be 3.7% and 0%, respectively.

This study utilizes a new adaptive sense current controller to get an accurate power supply. The proposed controller effectively reduces output ripple voltage of converters operated over the load current range. This reduction is realized using an adaptive sense current circuit that automatically adjusts the inductor current according to operational conditions. The proposed boost converter is designed and fabricated with a standard TSMC 3.3/5 V 0.35-µm 2P4M CMOS technology. The experimental results show that the power-conversion efficiency of the proposed boost converter is 2-5% higher than that of the conventional converter with a current-limited circuit. The proposed circuit greatly reduces (i.e. by 76%) output ripple voltage compared with the conventional circuit at a 10 mA loading current.