## 4 Conclusions  
The increasing adoption of electric vehicles has highlighted the need for efficient methods for generating, distributing, and managing the electrical power required to drive low-voltage automotive electronic components. In this study, we implemented a PCB-type SJB designed to stabilize the current supplied to the headlights used in low-voltage electronic systems in electric vehicles. The design incorporated a number of automotive semiconductor devices, and components were placed in a high-density arrangement to reduce the overall size of the final design. Finally, the SJB was equipped with a current sensing and diagnostic system that provides the driver with the information necessary to respond to failures or unintended situations.  
The heat distribution was simulated to determine the temperature distribution on the SJB module for various headlight loads. To reduce the effects of temperature on the individual circuits, the power and control units were designed as separate components and placed further apart in the module. An MCU and associated software program was implemented to monitor for abnormal states while driving the headlight load and to improve the power stability. The power loss of the headlight in the event of overvoltage was reduced by supplying PWM voltage with a variable duty cycle based on the 13.5 V power supply. In the event of the overvoltage exceeding 13.5 V, the PWM duty cycle control intervened to lower the rms value of the voltage, thereby ensuring that the voltage necessary for headlight operation is provided. A test environment was configured to evaluate the performance of the implemented SJB in terms of its on/off performance and PWM load control. Finally, a protective operation test was performed to experimentally confirm that the system was capable of diagnosing faults and of protecting the load in the event of open or short circuits.  
It should be noted that the SJB PCB module developed in this study was designed to support low-voltage (13.5 V) automotive electronic loads by miniaturizing and decreasing the weight of existing JBs, improving the vehicle stability by incorporating various fault diagnosis and monitoring functions, and increasing the data transmission stability by introducing CAN communications.  
In the future, we plan to apply the findings of this study to develop systems to support the high-voltage systems in electric vehicles that drive the traction motor and electric compressor by increasing the voltage and current handling capacity. We envision evolving the SJB implementation into a next generation intelligent box that integrates intelligent and high-voltage systems for driving loads in electric vehicles.  
Conceptualization, S.-W.B.; Methodology, S.-W.B. and S.W.L.; Software, S.-W.B. and S.W.L.; Validation, S.-W.B. and S.W.L.; Writing--original draft preparation, S.-W.B.; Writing--review and editing, S.W.L.; and S.-W.B.; Funding acquisition, S.-W.B. All authors have read and agreed to the published version of the manuscript.  
This study was supported by research fund from Honam University, 2019 and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2017R1C1B5075525).  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Headlight Load** & **Open Circuit Test** & **Short Circuit Test** \\ \hline H/LP High LH & Pass & Pass \\ H/LP Low RH & Pass & Pass \\ H/LP Low LH & Pass & Pass \\ H/LP High RH & Pass & Pass \\ Fog LH & Pass & Pass \\ Fog RH & Pass & Pass \\ \hline \hline \end{tabular}
\end{table}
Table 5: Results of protective operation tests.