Separating RGB Color Mixing From Overall Brightness Calibration

Equal numerical values for red, green, and blue LED channels do not necessarily produce neutral white or equal perceived contributions. LED spectra, efficiency, optics, and driver settings all influence the result. Separate channel mixing from overall brightness so calibration changes have a clear purpose.

Map the electrical controls

The TI LP5036 data sheet provides separate color mixing and brightness control functions. Understand how those controls combine in the selected configuration before building a calibration table or animation sequence.

Confirm the physical channel to color mapping with one channel enabled at a time. Include connector orientation and any board variants. A swapped color mapping can produce plausible mixed colors that make the error less obvious.

Establish a controlled optical setup

Use fixed distance, viewing geometry, diffuser, and ambient light conditions. Measure color and intensity with an instrument suitable for the requirement. A camera using automatic white balance can hide the very color error being investigated.

Characterize each primary over the useful control range, then measure the combined output. Keep the final optical stack in place where it affects mixing. Measurements of bare LEDs may not represent the assembled indicator or light guide.

Build the correction around a target

Define the desired color and brightness range. Adjust channel proportions to reach the color target, then use the appropriate common brightness control while checking that the color remains acceptable. Do not assume electrical linearity implies perceptually uniform steps.

Check whether corrections consume available range. If one channel reaches its maximum before the others, the target color may limit maximum achievable brightness. Document that tradeoff rather than silently clipping the channel command.

Verify temperature and low level behavior

Repeat after thermal stabilization and at representative low brightness settings. Quantization, current accuracy, and mode transitions can affect the result near the bottom of the range. Include relevant LED production variation if one calibration is intended to cover multiple assemblies.

Save channel mapping, current settings, optical geometry, target coordinates or another defined color criterion, and the final control table. Distinguish per-unit calibration from a common product setting. A useful result establishes the measured color and brightness behavior of the complete optical assembly, not merely a set of RGB numbers that looked acceptable on one sample. Keeping mixing and overall brightness separate also makes later firmware effects easier to change without unintentionally invalidating the calibrated color relationship. Include the calibration version with the hardware and LED population to which it applies.