Light driver calibration

1 . A charge voltage calibration system comprising:

a power supply;

a plurality of light sources coupled in series:

a driver coupled to the power supply and to the plurality of light sources, the driver comprising:

a capacitor;

a switch; and

a sense resistor;

wherein the switch, the sense resistor, and the plurality of light sources are coupled in series to form a discharge path; and

wherein the discharge path is coupled in parallel with the capacitor; and

a controller configured to:

cause the power supply to supply a first charge voltage to the driver; and

cause the switch to transition from an off state to an on state to discharge at least a portion of a first stored energy in the capacitor through the plurality of light sources.

2 . The charge voltage calibration system of claim 1 further comprising:

a digital-to-analog controller (DAC);

a comparator coupled to the DAC and to the sense resistor; and

wherein the controller is configured to control the DAC to provide a reference voltage to the comparator.

3 . The charge voltage calibration system of claim 2 further comprising a memory device; and

wherein the controller is configured to store a value of the first charge voltage in the memory device in response to detection by the comparator of a first discharge voltage generated across the sense resistor being greater than or equal to the reference voltage.

4 . The charge voltage calibration system of claim 3 , wherein the controller is further configured to:

set a target current value;

calculate a target discharge voltage to be generated across the sense resistor based on the target current value; and

control the DAC to provide the reference voltage based on the target discharge voltage.

5 . The charge voltage calibration system of claim 4 , wherein the target discharge voltage comprises a voltage expected to be generated across the sense resistor in response to a flow of current through the sense resistor equal to the target current value.

6 . The charge voltage calibration system of claim 4 , wherein the memory device comprises a lookup table; and

wherein the controller, in being configured to store the value of the first charge voltage, is configured to store a correlation of the first charge voltage with the target current value.

7 . The charge voltage calibration system of claim 4 further comprising a temperature sensor coupled to the controller; and

wherein the controller is further configured to:

receive a temperature value from the temperature sensor; and

store a relationship of the temperature value and the first charge voltage in the memory device.

8 . The charge voltage calibration system of claim 3 , wherein the controller comprises an input coupled to an output of the comparator; and

wherein the controller is configured to transmit a comparison signal from the output to the input, the comparison signal indicative of the first discharge voltage being greater than or equal to the reference voltage.

9 . The charge voltage calibration system of claim 8 , wherein the controller is further configured to store the value of the first charge voltage based on the comparison signal.

10 . The charge voltage calibration system of claim 8 , wherein the controller is further configured to:

cause the power supply to supply a second charge voltage to the driver in response to the comparison signal indicating that the first charge voltage less than the reference voltage.

11 . The charge voltage calibration system of claim 10 , wherein the second charge voltage is greater than the first charge voltage.

12 . The charge voltage calibration system of claim 10 , wherein the controller is further configured to:

cause the switch to transition from the off state to the on state to discharge at least a portion of a second stored energy in the capacitor through the discharge path, the at least a portion of the second stored energy based on the second charge voltage; and

store a value of the second charge voltage in the memory device in response to detection by the comparator of a second discharge voltage generated across the sense resistor being greater than or equal to the reference voltage.

13 . The charge voltage calibration system of claim 1 , wherein the plurality of light sources comprises light-emitting diodes.

14 . A method of calibrating illumination generated by a plurality of light sources, the method comprising:

controlling a power supply to output a first charge voltage to a light string driver coupled to the plurality of light sources;

storing a first capacitor voltage in a storage capacitor of the light string driver based on the first charge voltage;

controlling a switch of the light string driver into a conduction state to discharge at least a portion of the first capacitor voltage stored in the storage capacitor through the plurality of light sources, through the switch, and through a sense resistor; and

comparing a reference voltage with a resistor discharge voltage, the resistor discharge voltage generated across the sense resistor in response to the discharge of the at least a portion of the first capacitor voltage.

15 . The method of claim 14 further comprising, in response to the resistor discharge voltage being greater than or equal to the reference voltage, storing the first charge voltage in a lookup table of a memory device.

16 . The method of claim 15 further comprising:

calculating a target resistor discharge voltage to be generated across the sense resistor based on a target current value; and

controlling a digital-to-analog controller (DAC) to provide the reference voltage based on the target resistor discharge voltage.

17 . The method of claim 16 , wherein the plurality of light sources and the sense resistor are coupled in series to create a discharge path; and

further comprising calculating a target charge voltage based on an expected voltage to be generated across the discharge path in response to a current flow through the discharge path equal to the target current value.

18 . The method of claim 17 , wherein the first charge voltage is less than the target discharge voltage.

19 . The method of claim 18 , wherein, if the resistor discharge voltage is less than the reference voltage, the method further comprises:

controlling the power supply to output a second charge voltage to the light string driver, the second charge voltage greater than the first charge voltage;

storing a second capacitor voltage in the storage capacitor based on the second charge voltage;

controlling the switch into the conduction state to discharge at least a portion of the second capacitor voltage stored in the storage capacitor through the discharge path;

comparing the reference voltage with the resistor discharge voltage generated across the sense resistor in response to the discharge of the at least a portion of the second capacitor voltage; and

in response to the resistor discharge voltage being greater than or equal to the reference voltage, storing the second charge voltage in the lookup table.

20 . The method of claim 16 , wherein storing the first charge voltage in the lookup table comprises storing a relationship of the first charge voltage to the target current value in the lookup table.