Combined digital modulation and current dimming control for light emitting diodes

An apparatus comprising:

• first and second control paths, each control path configured to receive an input signal identifying a desired brightness for one or more light emitting diodes (LEDs), and to generate respectively a digital modulation control signal and a current control signal;
• the first control path configured to generate, for a range of lower LED brightness values, the digital modulation control signal, including adjusting the digital modulation control signal while maintaining the current control signal at a substantially constant value;
• the second control path configured to generate, for a range of higher LED brightness values, the current control signal, including adjusting the current control signal while maintaining the digital modulation control signal within a range of maximum values;
• a driver configured to drive the one or more LEDs according to the desired brightness, including transitioning between the digital modulation and current control signals based on LED brightness values.

A system comprising:

• one or more light emitting diodes (LEDs);
• a control unit comprising:
• first and second control paths, each control path configured to receive an input signal identifying a desired brightness for the one or more LEDs, and to generate respectively a digital modulation control signal and a current control signal;
• the first control path configured to generate, for a range of lower LED brightness values, the digital modulation control signal, including adjusting the digital modulation control signal while maintaining the current control signal at a substantially constant value;
• the second control path configured to generate, for a range of higher LED brightness values, the current control signal, including adjusting the current control signal while maintaining the digital modulation control signal within a range of maximum values;
• and
• a driver configured to drive the one or more LEDs according to the desired brightness, including transitioning between the digital modulation and current control signals based on LED brightness values.