The TPS61288 has a soft start function to prevent high inrush current during start-up. When the EN pin is pulled high, the internal soft-start capacitor is charged with a constant current. During this time, the soft-start capacitor voltage is compared with the internal reference (0.6 V). The lower one is fed into the internal positive input of the error amplifier. The output of the error amplifier (which determines the inductor peak current value) ramps up slowly as the soft-start capacitor voltage goes up. The soft-start phase is completed after the soft-start capacitor voltage exceeds the internal reference (0.6 V). When the EN pin is pulled low, the voltage of the soft-start capacitor is discharged to ground.