The device is designed to operate from an input voltage supply range between 2.7 V and 5.5 V. In a typical application this is from single Li-ion battery cell. This input supply should be well regulated and able to withstand maximum input current and maintain stable voltage without voltage drop even at load transition condition (start-up or rapid brightness change). The resistance of the input supply rail should be low enough that the input current transient does not cause drop below a 2.7-V level in the LP55231 supply voltage.