Example of regulating current of boost power supply in LED string

    In this configuration, the peripheral is configured as a fixed frequency power supply that generates most current modes. The COG is a complementary output generator. Its function is to generate complementary output through programmable dead zone composed of rising edge and falling edge inputs. The CCP is configured to generate a programmable frequency rising edge. When the current exceeds the output of the slope compensator, the comparator C1 generates a falling edge. The CCP can be combined with C1 to generate the duty cycle. Some topologies, such as boost, flyback, or SEPIC, require a duty cycle. OPA is used to provide feedback and compensation. In the figure, the DAC provides the reference voltage for the op amp, but if programmable voltage is not required, the fixed voltage reference (FVR) can also be used to provide the reference voltage for the op amp. The slope compensator can be reset by comparator or COG. Its working principle is to use programmable charging current to attenuate the capacitance from pre charging to the level set by its input (OPA in this example). This power configuration is very easy to use. The following is an example of regulating current of boost power supply in LED string.