Abstract: A ballast circuit suitable for driving an LED or similar load, comprises a primary switch mode converter, means for measuring a modulation, such as a phase cut, as used for dimming light levels, on an input AC supply, a current regulator positioned in series with the load, and a feedback controller for controlling operation of the switch mode controller based upon measured modulation levels. The feedback controller is adapted to interrupt normal switching of the switch mode converter if modulation levels detected lead to the ballast working at a lower than desired efficiency (deep dimming), or if voltage levels across the current regulator are higher than desired. The feedback controller may have a further feedback means for controlling switch mode parameters during lower levels of modulation (shallow dimming). The circuit allows large dimming levels to be achieved without generating appreciable light flicker in the load.

Abstract: The present application describes a driver circuit for supplying a drive current to an LED lighting scheme. In particular, the present invention relates to an AC input driver circuit operable in conjunction with a current regulator device which utilizes a plurality of Zener diodes connected in parallel combinations. The driver circuit comprises a feedback mechanism that is operable to maintain a constant voltage across the current regulator. Embodiments of the present invention seek to address LED ripple and, thus, optical flicker arising from an LED driver, connected at its input, to an AC supply.

Abstract: The present application describes a current regulator for providing a regulated current from an input voltage. The current regulator comprises a voltage regulator circuit, operable to provide a regulated voltage, which comprises a plurality of Zener diodes connected in parallel.

Abstract: The present application describes a current regulator for providing a regulated current from an input voltage. The current regulator comprises a voltage regulator circuit, operable to provide a regulated voltage, which comprises a plurality of Zener diodes connected in parallel.