Pulsed current averaging controller with amplitude modulation and time division multiplexing for arrays of independent pluralities of light emitting diodes

A system for regulating current in an electrical load, the system comprising:

• a converter coupled to the electrical load, the converter comprising a switch and an inductor to provide current to the electrical load;
• and
• a first controller coupled to the converter, the first controller to control the switch to provide current to the inductor for a first predetermined period of time and to provide current to the electrical load for a second predetermined period of time;
• to determine an average current provided to the electrical load during the second predetermined period of time;
• to compare the average current to a predetermined reference level;
• the first controller, when the average current is less than the predetermined reference level, to increase the first predetermined period of time for a next cycle by at least one first predetermined time increment, and when the average current is greater than the predetermined reference level during the second predetermined period of time, to determine a third period of time which elapses until the average current becomes less than the predetermined reference level, to determine an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and to decrease the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment.

An apparatus for regulating current in an electrical load, the apparatus for coupling to a converter to provide current to the electrical load through a switch and an inductor, the apparatus comprising:

• digital logic to control the switch to provide current to the inductor for a first predetermined period of time and to provide current to the electrical load for a second predetermined period of time;
• an integrator to determine an average current during the second predetermined period of time;
• and
• a comparator coupled to the integrator and to the digital logic, the comparator to compare the average current to a predetermined reference level;
• wherein the digital logic, when the average current is less than the predetermined reference level, further is to increase the first predetermined period of time for a next cycle by at least one first predetermined time increment, and when the average current is greater than the predetermined reference level during the second predetermined period of time, to determine a third period of time which elapses until the average current becomes less than the predetermined reference level, to determine an integer corresponding to a ratio of the third period of time to the second predetermined period of time, and to decrease the first predetermined period of time for the next cycle by the integer multiple of the first predetermined time increment.

A method of regulating current in an array of independent pluralities of light emitting diodes of corresponding colors, the method comprising:

• modulating a current amplitude and a duration of time division multiplexing for each independent plurality of light emitting diodes of the array;
• maintaining a substantially constant average current level to the plurality of light emitting diodes of the array;
• determining an average DC current for expected color and brightness for each independent plurality of light emitting diodes of the array;
• and
• determining a predetermined reference level as the sum of all DC currents for each independent plurality of light emitting diodes of the array.

A system for regulating current in an array of independent pluralities of light emitting diodes of corresponding colors, the system comprising:

• a multiplexer to switch current to each independent plurality of light emitting diodes of the array;
• a first controller to maintain a substantially constant average current level to the plurality of light emitting diodes of the array;
• and
• a second controller coupled to the multiplexer and to the first controller, the second controller to modulate a current amplitude and a duration of time division multiplexing of current for each independent plurality of light emitting diodes of the array, to determine an average DC current for expected color and brightness for each independent plurality of light emitting diodes of the array, and to determine a predetermined reference level as the sum of all DC currents for each independent plurality of light emitting diodes of the array.