## 1 Introduction
As Figure 2a shows, this technique is based on using two converters: a low-switching-frequency DC/DCconverter, acting as an HB-LED driver and the other high-switching-frequency and fast-response DC/DC converter, providing the communication tasks. In this case additional signal distortion is introduced by the switching frequency, too. This configuration leads to a partial power conversion between the two converters, where the power is divided depending on the task. The architecture proposed in [22] uses a regular Buck DC/DC converter with low switching frequency operation for lighting tasks and a two-phase Buck DC/DC converter with high-order output filter, operating at high switching frequency for communication tasks. The main drawback is the need for two input voltage sources, one of which is isolated, for the real implementation, adding hardware complexity to the design of the previous stages of the power supply chain. Following this technique other approaches could be taken, as shown in Figure 2b, using isolated DC/DC converters. However, any configuration based on an isolated DC/DC converter for splitting power introduces the same hardware complexity as mentioned above, but in the last step of the power supply chain: the VLC driver. The objective of this work is the proposal of a new architecture of a VLC driver based on the split power technique. The idea is to use the same partial power conversion between two DC/DC converters to achieve high efficiency in the VLC driver, improving on the performance of traditional Buck DC/DC converter solutions and overcoming the hardware complexity of traditional schemes based on split power [22]. To take advantage of the integration between VLC and SSL infrastructure, this work focuses on VLC drivers for HB-LEDs, meaning that the maximum bandwidth needed is limited to 5 MHz. This paper introduces a high-efficiency HB-LED driver for VLC based on the Two-Input Buck (TIBuck) DC/DC converter. The proposed TIBuck DC/DC converter only needs one input voltage source to naturally split the power with high efficiency and high communication capability, overcoming the weakness of previous approaches because no galvanic isolation is needed and, therefore, the hardware complexity is simplified. Therefore, the main advantages for splitting the power are reached naturally. The lower switching harmonic components and higher duty cycle resolution of the TIBuck DC/DC converter allows good communication performance from the VLC driver. Moreover, the lower voltage stress across switches achieves high efficiency. Power is split by means of an auxiliary Buck DC/DC converter, which is in charge of generating the secondary voltage source needed by the TIBuck DC/DC converter. This gives the division of the tasks regarding power conversion. Due to the separation of tasks, each converter has different requirements, allowing further optimization of each, according to its task. The paper is organized as follows. Section 2 reviews the operating principles of the TIBuck DC/DC converter, highlighting its main advantages over Buck DC/DC converters for use as a VLC driver. Section 3 describes the proposed VLC driver based on split power with only one input voltage source, using both an auxiliary Buck DC/DC converter and a TIBuck DC/DC converter. Section 4 covers a theoretical efficiency study, which is needed both to identify the amount of the power for switching and the amount of power that  
Figure 2: Two implementation examples of the split power technique: (**a**) with two isolated input voltage sources, one of them isolated (in [22]). (**b**) With an isolated DC/DC converter in the VLC driver structure. comes up to the load directly. This identification means that the power conversion made at different switching frequencies can be quantified. The objective is to maximize efficiency by keeping the communication features of the VLC driver (i.e., communication capability and resolution) at a maximum. The experimental results are given in Section 5, and finally, the conclusions are described in Section 6.