Illumination device and method for avoiding an over-power or over-current condition in a power converter

A method for controlling a lumen output of an illumination device comprising a plurality of light emitting diode (LED) chains and a plurality of power converters, so as not to exceed a maximum safe power level and a maximum safe current level of the power converters at a present temperature, the method comprising:

• measuring a the present temperature associated with the at least one power converter;
• determining the maximum safe current level and the maximum safe power level of the power converters at the present temperature;
• and
• adjusting drive currents supplied to each of the plurality of LED chains, so as not to exceed the maximum safe current level and the maximum safe power level at the present temperature;
• receiving a chromaticity setting and a brightness setting for the illumination device;
• determining a maximum lumens value that can be safely produced by all LED chains at a predetermined safe temperature to achieve the chromaticity setting;
• and
• determining a target lumens value that can be safely produced by all LED chains at the present temperature to achieve the chromaticity setting without exceeding the maximum safe current level or the maximum safe power level associated with the power converters.

A controller for an illumination device, the controller comprising:

• a control circuit coupled to a light-emitting diode (LED) driver circuit, wherein the control circuit is configured for determining a present temperature of the illumination device, and adjusting respective drive currents supplied by the LED driver circuit to a plurality of LED chains, so as not to exceed a maximum safe current level or a maximum safe power level of a power supply providing power to the LED driver circuit at the present temperature;
• and
• an interface coupled to the control circuit and coupled for receiving a chromaticity setting;
• wherein the control circuit is further configured for determining a maximum lumens value that can be safely produced by the plurality of LED chains at a predetermined safe temperature to achieve the chromaticity setting;
• and
• wherein the interface is further coupled for receiving a brightness setting, and the control circuit is further configured for determining a target lumens value that can be safely produced by the plurality of LED chains at the present temperature to achieve the chromaticity setting without exceeding the maximum safe current level or the maximum safe power level of the power supply.

A method for controlling a lumen output of an illumination device, the method comprising

• measuring, by temperature sensing circuitry, a present temperature of the illumination device;
• adjusting, by control circuitry communicatively coupled to the temperature sensing circuitry, drive currents supplied to each of a plurality of light-emitting diode (LED) chains, so as not to exceed a maximum safe current level or a maximum safe power level of a power supply operatively coupled to the plurality of LED chains, at the measured present temperature;
• receiving, via interface circuitry communicatively coupled to the control circuitry, a target chromaticity setting and a target brightness setting for the illumination device;
• determining a maximum lumens value that can be safely produced by the plurality of LED chains at a predetermined safe temperature to achieve the target chromaticity setting;
• and
• determining a target lumens value that can be safely produced by the plurality of LED chains at the measured present temperature to achieve the target chromaticity setting without exceeding the maximum safe current level or the maximum safe power level of the power supply.

A controller for an illumination device, the controller comprising:

• a control circuit coupled to one or more light-emitting diode (LED) driver circuits, the control circuit configured to:
• measure, via temperature sensing circuitry communicatively coupled to the control circuit, a present temperature of the illumination device;
• determine a scale factor to be applied to the respective drive currents of each of a plurality of LED chains to achieve a target chromaticity setting for the illumination device without exceeding a maximum current level of the one or more LED driver circuits at the measured present temperature;
• determine a maximum lumens value that can be produced by the plurality of LED chains to achieve the target chromaticity setting for the illumination device without exceeding the maximum current level of the one or more LED driver circuits at the measured present temperature;
• determine, based on the scale factor, the maximum lumens value, and a target brightness setting, a target lumens value that can be produced by the plurality of LED chains to achieve the target chromaticity setting for the illumination device without exceeding the maximum current level of the one or more LED driver circuits at the measured present temperature;
• update the target lumens value in response to a change in the target chromaticity setting, the brightness setting, or the measured present temperature;
• and
• adjust, based on the scale factor and the maximum lumens value, the respective drive currents supplied to each of the plurality of LED chains to achieve the target lumens value;
• and
• an interface communicatively coupled to the control circuit to receive the target chromaticity setting or the target brightness setting.