7.3.2.5.2 Openloop Voltage

in some case, there is no control loop for the buck converter through the LED. To prevent the output voltage of the buck converter to vary inconsistently, use an internal resistive divider to close the loop is closed as shown in Figure 4. Open loop voltage control is active:

• during the BBM period. Transitions from one LED to another implies that during the BBM time all LEDs are off.
• when the current setting for all three LEDs is 0.

It’s important to set the open loop voltage to approximately equal the lowest LED forward voltage. Use register 0x18 to set the open loop voltage between 3 V and 18 V in steps of 1 V.