## 1 Introduction
Figure 3: The equivalent circuit for operation mode 1 of the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications. Figure 6: The equivalent circuit for operation mode 4 of the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications. Operation Mode 1 (\(t_{0}\leq t<t_{1}\)): Figure 3 shows an equivalent circuit diagram for operation mode 1 of the proposed UV-C LED lamp driver applied to a DC voltage for sterilization and germicidal applications. At time \(t_{0}\), the power switch \(S\) is activated, causing diode \(D_{1}\) to be reverse-biased. The input voltage source \(V_{IN}\) then supplies energy to the magnetizing inductor \(L_{M}\), the primary-side leakage inductance \(L_{K1}\), and the energy storage capacitor \(C_{1}\) through switch \(S\). Meanwhile, diode \(D_{2}\) remains forward-biased, continuing its previous operation, allowing energy to transfer from the secondary-side  
Figure 7: Key waveforms of the proposed UV-C LED lamp driver circuit applied to a DC-input voltage source for sterilization and germicidal applications. leakage inductance \(L_{K2}\) to capacitor \(C_{2}\) via diode \(D_{2}\). Both capacitors \(C_{1}\) and \(C_{2}\) provide energy to the UV-C LED lamp for sterilization and germicidal applications. When the current through \(L_{K2}\) drops to zero at \(t_{1}\), mode 1 of the operation concludes. Operational Mode 2 (\(t_{1}\leq t<t_{2}\)): Figure 4 shows an equivalent circuit diagram for operation mode 2 of the proposed UV-C LED lamp driver applied to a DC voltage for sterilization and germicidal applications. At \(t_{1}\), the power switch \(S\) remains on, allowing the input voltage source \(V_{IN}\) to continue supplying energy to the magnetizing inductor \(L_{M}\), the primary-side leakage inductance \(L_{K1}\), and capacitor \(C_{1}\) via switch \(S\). Additionally, capacitors \(C_{1}\) and \(C_{2}\) continue to power the UV-C LED lamp for sterilization and germicidal applications. When the power switch \(S\) turns off at \(t_{2}\), mode 2 of the operation concludes, and the current in the magnetizing inductor \(i_{LM}\) reaches its peak value. Operational Mode 3 (\(t_{2}\leq t<t_{3}\)): Figure 5 shows an equivalent circuit diagram for operation mode 3 of the proposed UV-C LED lamp driver applied to a DC voltage for sterilization and germicidal applications. At \(t_{2}\), once the power switch \(S\) is turned off, diode \(D_{1}\) becomes forward-biased, allowing the magnetizing inductor \(L_{M}\) and the primary-side leakage inductance \(L_{K1}\) to transfer energy to capacitor \(C_{1}\) through diode \(D_{1}\). Simultaneously, the secondary-side leakage inductance \(L_{K2}\) supplies energy to capacitor \(C_{2}\) via diode \(D_{2}\). Both capacitors \(C_{1}\) and \(C_{2}\) continue to power the UV-C LED lamp for sterilization and germicidal applications. When the current in the primary-side leakage inductance \(i_{LK1}\) reaches zero at \(t_{3}\), mode 3 of the operation concludes. Operational Mode 4 (\(t_{3}\leq t<t_{4}\)): Figure 6 shows an equivalent circuit diagram for operation mode 4 of the proposed UV-C LED lamp driver applied to a DC voltage for sterilization and germicidal applications. At \(t_{3}\), with the power switch \(S\) still off, the magnetizing inductor \(L_{M}\) and the secondary-side leakage inductance \(L_{K2}\) supply energy to capacitor \(C_{2}\) through diode \(D_{2}\). Additionally, capacitors \(C_{1}\) and \(C_{2}\) continue to power the UV-C LED lamp for sterilization and germicidal applications. When the power switch \(S\) turns on again at \(t_{4}\), mode 4 concludes, and the magnetizing inductor current \(i_{LM}\) reaches its minimum value. At this point, the circuit returns to operation mode 1. Design Considerations of Key Parameters in the Proposed UV-C LED Lamp Driver Circuit Applied to a DC-Input Voltage for Sterilization and Germicidal Applications