Variable Frequency Constant Current Control Method for Switched-Capacitor Converter Based Automotive LED Driver

A variable-frequency constant-current control (VFCCC) method with the constant ON-time is proposed in this paper for a switched-capacitor (SC) converter-based automotive LED driver. This control method is based on the one-cycle control method. The stable load current regulation could be achieved with the simple analog topology. The variable load current is conveniently set by changing the reference value. In order to reduce the current spikes, the SC topology presented in this paper introduces an inductor in the charge loop. To verify the performance of the proposed control method, a 36-W SC converter is constructed. The VFCCC-controlled SC converter is tested under different operation conditions with the different input voltages and variable constant ON-time. The experimental and simulated results show that with the proposed control method, the external disturbance could be rejected with the fast-dynamical response speed and robust performance. With the SC converter, the high-power density could be realized for the automotive LED driver. The VFCCC control method is suited for the different topologies of SC converters. It could facilitate the SC applications for the automotive LED driver.