System and method for uniform control of current regulated outputs over wide voltage ranges
View Patent ↗A digital control mechanism is provided to maintain current matching of a plurality of LED devices where the conventional supply voltage may be insufficient to achieve the threshold working current.
1. A control system to maintain a uniform brightness across a plurality of LED output channels each employing individual current sources comprising:
a device for making a sampled comparison of error signals derived from individual error amplifiers associated with each said LED output channel and in response to the error signals: and
a controller for making adjustments to individual currents supplied to each said LED output channel in response to the error signals to steer current toward producing uniform LED brightness,
wherein a digital control loop is modified to reduce a rate increase of an output current compared to a rate decrease of the output current to allow a circuit to regulate better in presence of noise or frequent power supply dips.
2. A control system according to claim 1 ,
wherein the individual input sources are of unregulated voltage.
3. A system according to claim 1 wherein said device includes a current controller and at least one current sense resistor, the current controller being configured to make adjustments for varying value of said at least one current sense resistor.
4. A system according to claim 1 wherein three samples are made to further improve resultant operating LED current level.
5. A method to control LEDs and to maintain a uniform brightness across multiple LED channels using individual current sources comprising:
making a sampled comparison of error signals derived from error amplifiers associated with each output channel; and
adjusting current through the LEDs in response to the error signals to steer current toward producing uniform brightness,
wherein the individual input sources are of unregulated voltage, and
wherein a digital control loop is modified to reduce a rate increase of an output current compared to a rate decrease of the output current to allow a circuit to regulate better in presence of noise or frequent power supply dips.
6. A method to control LEDs and to maintain a uniform brightness across multiple LED channels using individual current sources comprising:
making a sampled comparison of error signals derived from error amplifiers associated with each output channel; and
adjusting current through the LEDs in response to the error signals to steer current toward producing uniform brightness,
wherein a digital control loop is modified to reduce a rate increase of an output current compared to a rate decrease of the output current to allow a circuit to regulate better in presence of noise or frequent power supply dips.
7. The method according to claim 6 wherein three samples are made to further improve resultant operating LED current level.