Abstract: This disclosure relates to illumination systems. In particular it relates to a method and system for avoiding flicker (in particular 100 Hz or 120 Hz flicker) in solid state lighting devices such as LED or OLED assemblies. A controller for a driver circuit of a solid state lighting device (SSL) is described. The driver circuit comprises a power converter to convert a varying input voltage into a drive voltage for the SSL device. The input voltage is derived from a rectified AC mains voltage and frequency. The power converter is used with a maximum voltage step-up conversion ratio. The controller synchronizes to the mains frequency and determines a plurality of pulse intervals repeated at a pulse frequency where the pulse frequency is greater than a perceptual frequency of light intensity variations perceivable by a human eye.

Abstract: The present document relates to switched power supplies. In particular, the present document relates to a method and system for controlling a bypass transistor in a DC-to-DC converter. A power converter configured to convert an input voltage at an input of the power converter into an output voltage at an output of the power converter is described. The power converter comprises a DC-to-DC converter comprising a high side switch; a bypass transistor parallel to the DC-to-DC converter, configured to couple a load at the output of the power converter to the input voltage during an on-state of the bypass transistor; and current sensing means configured to sense a current through the high side switch; wherein the bypass transistor is controlled based at least on the sensed current through the high side switch.

Abstract: The present document relates to a method and system for dimming low power illumination devices, such as LED (Light Emitting Diode) assemblies. A controller for a driver circuit of a light source is described. The driver circuit controls a plurality of illumination states of the light source using a power converter, which converts power from an input voltage waveform of a mains power supply into a drive signal for the light source. The controller comprises an event detection unit; a state register to store an indication of a current state of the illumination states; a state processor to determine a target state of the illumination states, based on the detected event and based on the current state; and an output control unit controls the power converter of the driver circuit to provide a drive signal for the target state.