In DC-DC converters the Soft Start may be used to program how slowly the converter turns on. In the most cases this is realized by an internal or external capacitor. The voltage on this capacitor clamps the error amplifier, causing the output voltage to ramp up.
At turn on, the capacitor is completely discharged. There is a charge interval during which the converter is completely off. This is known as the turn on delay interval. Then, the capacitor voltage traverses the active region. The capacitor voltage level in the active region depends on the load condition of the DC/DC Converter. If the converter is lightly loaded, the error amplifier voltage required to produce full regulated output is relatively low. Therefore, the transition through the active region is relatively fast. If the converter is fully loaded, the error amplifier voltage required to produce full regulated output is relatively high. Therefore, the transition through the active region is relatively slower.