Circuits and methods for controlling solid state lighting

A method of operating a dimmable solid state lighting apparatus including a plurality of light-emitting devices (LEDs) coupled together in a string including a first LED segment configured to emit a first chromaticity light coupled across a first bypass circuit, a second LED segment configured to emit a second chromaticity light coupled across a second bypass circuit, and an additional LED segment configured to emit an additional chromaticity light coupled across an additional bypass circuit, the method comprising:

• receiving a dimming input to adjust light emitted by the string;
• determining a string current value indicating a current in the string developed responsive to the dimming input;
• stabilizing the string current value to provide a stabilized string current value;
• and then
• providing modulation control signals to bypass circuit across the LED segments based on the stabilized string current value to configure the string to emit an additional v′ shift in a chromaticity value of light to vary substantially in conformance with a Planckian locus in response to the dimming input.

A solid state lighting apparatus including a plurality of light-emitting devices (LEDs) electrically coupled together in at least one string, the apparatus comprising:

• a first LED segment in a first string configured to emit a first chromaticity light, coupled across a first bypass circuit;
• a second LED segment in the first string configured to emit a second chromaticity light, coupled across a second bypass circuit;
• an at least one additional LED segment configured to emit an additional chromaticity light, coupled across an additional bypass circuit;
• and
• a control circuit configured to modulate the at least one additional bypass circuit, to cause the lighting apparatus to emit an additional v′ shift in a chromaticity value of light emitted by the string to vary substantially in conformance with a Planckian locus in response to an input to change the chromaticity value of light emitted by the string.