## 1 Introduction
[27] proposed a single-switch LED driver circuit suitable for battery-operated systems. In response, this paper develops and implements an innovative electronic driver for UV-C LED disinfection and sterilization lamps using a DC-input voltage source, which extends as well as further improves on the literature [28]. Compared to conventional two-stage power conversion designs, this approach reduces the number of power switches and components required, lowers the driver circuit's cost, and enhances energy conversion efficiency. This paper is structured as follows. Section 2 presents the proposed UV-C LED lamp driver designed for sterilization and germicidal applications using a DC-input voltage, including an analysis of its operational modes. Section 3 provides design guidelines and considerations for key circuit parameters in the UV-C LED lamp driver. Section 4 discusses the UV-C LED lamp used for sterilization and germicidal purposes and presents experimental results from the prototype driver circuit, tested with a DC-input voltage source. Section 5 discusses the characteristics of the deep-ultraviolet LED sterilization and disinfection modules used in this paper compared to those used in the previous literature, and the novelty and advantages of the proposed LED power supply over existing LED power supplies. Finally, Section 6 offers concluding remarks. Descriptions and Operational Mode Analysis of the Proposed UV-C LED Lamp Driver Applied to a DC-Input Voltage for Sterilization and Germicidal Applications  
Figure 1 shows the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications, which is named the modified buck-flyback converter; it integrates a buck converter with a flyback converter into a  
single-stage DC-DC power conversion topology and includes a power switch \(S\), two diodes (\(D_{1}\) and \(D_{2}\)), a transformer \(T_{R}\) with a primary-side turn \(N_{1}\) and a secondary-side turn \(N_{2}\), two output capacitors (\(C_{1}\) and \(C_{2}\)), and a UV-C LED lamp for sterilization and germicidal applications. Figure 2 presents the equivalent circuit of the proposed UV-C LED lamp driver, designed for use with a DC-input voltage source in sterilization and germicidal applications. This circuit model was obtained through an analysis of the operational modes of the proposed design. The following assumptions were applied to facilitate the circuit operation analysis:  
1. The magnetizing inductor \(L_{M}\) of the transformer \(T_{R}\) is designed to operate in continuous conduction mode (CCM), which means that the minimum value of the current \(I_{LM}\) of the magnetizing inductor is above zero. Here, \(L_{K1}\) and \(L_{K2}\) represent the primary and secondary leakage inductances of the transformer \(T_{R}\), respectively. 2. The energy storage capacitors \(C_{1}\) and \(C_{2}\) are assumed to have sufficient capacity, allowing the output voltage to be treated as a constant. 3. All remaining circuit components are considered ideal. Figures 3-7 show the operating modes and key waveforms of the UV-C LED lamp driver applied to a DC-input voltage source for sterilization and germicidal applications, respectively, and the operational analysis is described in detail below. Figure 1: The proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications. Figure 2: The equivalent circuit of the proposed UV-C LED lamp driver applied to a DC-input voltage source for sterilization and germicidal applications. Figure 4: The equivalent circuit for operation mode 2 of the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications. Figure 5: The equivalent circuit for operation mode 3 of the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications.