In this paper, an LLC-C resonant converter is proposed. Utilizing the topology-morphing technology, the converter is able to integrate two circuits into one novel topology. It has the advantages the two circuits have, while averting their drawbacks. At rated, the converter operates as an LLC circuit, and high rating efficiency is easy to obtain; when the input voltage is high, the LCCL circuit is used instead, providing wide gain range with relatively high efficiency. Experiments are conducted to verify the feasibility: when the input voltage varies from 110 V to 400 V, the output voltage is constant at 200 V (gain range from 1.8 to 0.5). The efficiency is always beyond 90%, and the highest point reaches 97.5%. The good nature of wide gain range and high efficiency makes the proposed converter suitable for the applications, where voltage range and efficiency are required strictly.