## 5 Experimental Results  
Figures 7-13 shows the waveforms related to the proposed LED driver at rated condition. Figure 7 shows the gate driving signal for \(Q_{1}\), \(v_{gs}\), the voltage on \(Q_{1}\), \(v_{ds}\), and the current in \(L\). Figure 8 shows the gate driving signal for \(Q_{1}\), \(v_{gs}\), the voltages across \(C_{1}\), \(C_{2}\), and \(C_{3}\), called \(V_{C1}\), \(V_{C2}\), and \(V_{C3}\), respectively. Figure 9 shows the gate driving signal for \(Q_{1}\), \(v_{gs}\), and the voltages across \(C_{4}\) and \(C_{5}\), called \(V_{C4}\) and \(V_{C5}\), respectively. Figure 10 shows the gate driving signal for \(Q_{1}\), \(v_{  
Figure 12: Measured waveforms at rated load: (1) \(v_{gs}\); (2) \(i_{C1}\); (3) \(i_{C2}\); (4) \(i_{C3}\). Figure 14: Measured waveforms at rated load: (1) \(V_{o1}\); (2) \(i_{LS1}\); (3) \(V_{o2}\); (4) \(i_{LS2}\). Figure 13: Measured waveforms at rated load: (1) \(v_{gs^{\prime}}\) (2) \(i_{C4}\); (3) \(i_{C5}\). From Figure 7, the input inductor \(L\) operates in the CCM. From Figures 7, 10 and 11, the voltages across \(Q_{1}\), \(D_{2}\), \(D_{4}\), and \(D_{6}\) have voltage rings during the turn-off transient of \(Q_{1}\), due to resonance among the body capacitance of \(Q_{1}\), the diode parasitic capacitances of \(D_{2}\), \(D_{4}\), and \(D_{6}\), and the line parasitic inductances. From Figure 8, the voltages across \(C_{1}\), \(C_{2}\), and \(C_{3}\) are fixed at some values, whereas from Figure 9, the voltages across \(C_{4}\) and \(C_{5}\) are kept close to zero. From Figures 10 and 11, the voltages across \(D_{1}\), \(D_{3}\), and \(D_{5}\) have voltage rings during the turn-on transient of \(Q_{1}\), due to resonance among the diode parasitic capacitances of \(D_{1}\), \(D_{3}\), and \(D_{5}\), and the line parasitic inductances. From Figures 12 and 13, the currents flowing through \(C_{1}\) to \(C_{5}\) have negative current rings since the voltages across \(D_{1}\), \(D_{3}\), and \(D_{5}\) have voltage rings during the turn-on transient of \(Q_{1}\), whereas the current flowing through \(C_{1}\) to \(C_{5}\) have positive current rings since the voltages across \(D_{2}\), \(D_{4}\), and \(D_{6}\) have voltage rings during the turn-off transient of \(Q_{1}\). From Figures 14-16, the current sharing between LEDs performs well, and the corresponding voltages across \(LS_{1}\) to \(LS_{6}\) are almost the same due to all LED strings being almost identical. In addition, Tables 3-5 show the current sharing error percentage (CSEP) under an input voltage of 12 V and different current levels in LED strings. The definition of CSEP is shown as follows:  
\[\text{CSEP}_{y}=\frac{I_{LSy}-(\sum\limits_{x=1}^{m}I_{LSx})\div m}{(\sum \limits_{x=1}^{m}I_{LSx})\div m}\times 100\% \tag{33}\]  
where \(\text{CSEP}_{y}\) is the CSEP of the \(y\)-\(th\) LED string, \(m\) is the total number of LED strings, \(I_{LSy}\) is the current flowing through the \(y\)-\(th\) LED string, and \(\sum\limits_{x=1}^{m}I_{LSx}\) is the sum of all the currents flowing through the LED strings. Based on the calculated measurements from Tables 3-5, the CSEP values for any load locate between \(-1\%\) and \(1\%\). Therefore, the proposed LED driver has a good capability of current sharing. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \(LS_{1}\) & \(LS_{2}\) & \(LS_{3}\) & \(LS_{4}\) & \(LS_{5}\) & \(LS_{6}\) \\ \hline \(I_{LS}\) (mA) & 85.4 & 86 & 85.2 & 86.6 & 85.3 & 86.5 \\ \(V_{LED}\) (V) & 10.7 & 11.4 & 10.6 & 11.5 & 10.6 & 11.5 \\ Error (\%) & \(-0.5\) & 0.2 & \(-0.73\) & 0.9 & \(-0.62\) & 0.78 \\ \hline \end{tabular}
\end{table} 
Table 3: Associated current sharing error percentage (CSEP) measurements at minimum load. In the following, how to measure the efficiency of the proposed LED driver is described. As shown in Figure 17, one current sensing resistor is in series with the input current path. First, a digital meter, called Fluke 8050A, is used to measure the voltage across this resistor so as to obtain the value of the input current.