Precise and full-range dimming control for an offline single-inductor-multiple-output LED driver

In this paper, PWM dimming is studied for an offline single-inductor-multiple-output (SIMO) LED driver at the string level (i.e., only one power channel is active) and at the system level (i.e., all power channels are active). The issues of employing PWM dimming over a SIMO LED driver are investigated and the corresponding solutions are proposed. With the proposed dimming technique, a SIMO LED driver can achieve a high dimming precision (with a tolerance of 0.8%) and a full dimming range (0%–100%) for each power channel. The proposed PWM dimming method has been practically verified with a 25 W off-line SIMO LED driver prototype.