Small Signal Modeling and Transient Cross-Regulation Analysis of Peak-Current-Mode-Controlled SIDO Buck LED Driver

Single-inductor dual-output (SIDO) dc–dc converter has been applied to light-emitting diode (LED) drivers with its advantages of small volume and low cost. Peak-current-mode (PCM) control of the SIDO converter has the advantages of fast transient performance and suppressed cross-regulation. A PCM-controlled SIDO buck LED driver to achieve independent dimming and to eliminate the steady-state cross-regulation is proposed in this article. The circuit and the principle of the PCM-controlled SIDO buck LED driver are presented, and its small signal model is established based on inductor current ripple. Furthermore, based on control-to-output loop gain transfer functions, control parameters of PCM-controlled SIDO buck LED driver are designed to achieve independent output current regulation of each LED driver. Besides, cross-regulation transfer functions are obtained to investigate the effect of reference signals and control parameters on the transient cross-regulation. Moreover, the effect of capacitor parameters on the stability of the LED driver is analyzed based on the bifurcation diagram. Finally, experimental results are provided to show the independent dimming capability of PCM-controlled SIDO buck LED driver with designed parameters, and the validity of the theoretical analysis on transient cross-regulation and stability of the LED driver.