DLPS052 October 2015 DLPA3000
Several situations exist in which the control loop for the buck converter via the LED is not present. In order to prevent the output voltage of the buck converter to run-away, the loop is closed by means of an internal resistive divider (see Figure 5 - Openloop feedback circuitry). Situations in which the openloop voltage control is active:
It is advised to set the openloop voltage to about the lowest LED forward voltage. The openloop voltage can be set between 3 V and 18 V in steps of 1 V through register 0x18.