An LED lamp comprising: a plurality of LED strings, each LED string comprising a plurality of LEDs; a plurality of constant current circuits for powering the plurality of LED strings, wherein one constant current circuit is provided for each LED string; a plurality of shift registers for controlling the operation of the plurality of constant current circuits, wherein at least one shift register is provided for each LED string; and a microprocessor for supplying timing pulses to the plurality of shift registers for controlling operation of the plurality of constant current circuits, the timing pulses comprising a plurality of serial bit streams.