The TPSM86325x has an internal fixed 1.6ms soft-start time. The EN default status is low. When the EN pin becomes high, the internal soft-start function begins ramping up the reference voltage to the PWM comparator.

If the output capacitor is prebiased at start-up, the devices initiate switching and start ramping up only after the internal reference voltage becomes higher than the feedback voltage, V_FB. This scheme makes sure that the converter ramps up smoothly into the regulation point.