Intelligent AC Fixture Lighting

The variety of interfaces and combined functionality make these products the core of intelligent lighting products. Integrated into a 4x4mm QFN package are three separate systems functions: (1) power factor correction, (2) LED brightness control, and (3) auxiliary power generation.

The PFC function is compatible with conduction angle dimmers, obtains a power factor greater than 0.95 and creates a signal that may be used to control the LED brightness.

The brightness control section features user-input signals for touch button brightness control, conduction-angle to brightness translation, direct LED modulation, and LED temperature sensing to eliminate over temperature concerns. On-chip digital filtering creates smooth transitions from off to on and across the brightness range. The filtering mimics the time constant of an incandescent bulb and eliminates line-sag flickering.

The auxiliary power section generates 12 Volts from the AC line voltage and provides the system designer the flexibility to power external communication and control functions independently from the LED on-off status or brightness. This allows continuous command, control, and communication with the lighting resource regardless of the brightness state. The 908 and 909 differ in the way the auxiliary power is managed. The 908 always generates the auxiliary power when any power is applied to the part. The 909 only generates auxiliary power when the EN input is enabled.