SNVSBC9B November 2019 – August 2020 TPSM53604
In light load conditions, the device turns on the high-side MOSFET until the inductor current reaches a controlled minimum value of approximately 1 A. As the input voltage decreases, reducing the voltage headroom between VIN and VOUT, the amount of time required to reach this minimum current increases. During this time, additional energy flows from VIN to VOUT, resulting in increased output voltage ripple. To eliminate this behavior, the EN UVLO function must be used to maintain at least 1 V of headroom above VOUT. Alternatively, additional output capacitance can be added to reduce the output voltage ripple in applications that operate at light loads with very low VIN to VOUT headroom.