LED controller, LED drive system and method

A light emitting diode (LED) drive system, comprising:

• an LED arrangement,
• a power supply configured to supply the LED arrangement with power,
• a series switch coupled between the LED arrangement and the power supply, and
• a controller comprising:
• a control terminal to be coupled to the series switch between the power supply and the LED arrangement, wherein the LED arrangement is switchable between a first set of active LEDs and a second set of active LEDs,
• an input terminal configured to receive a measure of a current through the series switch, and
• a control circuit configured to, upon switching of a number of active LEDs from the first set to the second set, output a control signal at the control terminal to repeatedly switch the series switch off and on during a transition period, wherein the control circuit is configured such that the transition period ends when the measure indicates that the current remains below a predefined threshold.

A method of supplying a light emitting diode (LED) arrangement with power, the method comprising:

• operating the LED arrangement with a first set of active LEDs,
• switching the LED arrangement from the first set of active LEDs to a second set of active LEDs,
• in response to the switching of the LED arrangement, repeatedly switching a series switch between a power supply and the LED arrangement off and on during a transition period,
• measuring a current through the series switch,
• ending the transition period when the current remains below a predefined threshold, and
• operating the LED arrangement with the second set of active LEDs after the transition period.