An integrated multilevel converter with sigma delta control for LED lighting

LEDs are rapidly emerging as the dominant light source. As such, the lighting industry values power converters with high efficiency, unity power factor, minimal flicker, dimming, low cost, and small form factor. This paper presents an integrated circuit (IC) LED driver that is designed to achieve these goals. It also introduces multilevel converters with sigma delta modulation to the power IC space. The circuit features a pair of sigma delta controlled multilevel converters. The first is a multilevel rectifier responsible for power factor correction (PFC) and dimming. The second is a multilevel inverter used to cancel AC power ripple from the DC bus. The system also contains an output stage that powers the LEDs with DC and provides for galvanic isolation. The proposed IC LED driver has been simulated and prototyped on a silicon fabrication process. Its functional performance indicates that integrated multilevel converters are a viable topology for lighting and other similar applications.