For the analog output voltage tracking, a voltage applied to the SS/ATRK pin overwrites the reference voltage for the output regulation loop. Although it is possible, it is not recommended to apply this voltage before the soft start is finished because the soft-start ramp time and, therefore, the input current during the start-up is changed.

As the internal error amplifier is designed to use the lowest reference input voltage, the applied voltage on the SS/ATRK pin is only effective for voltages lower than the V_ref of the feedback pin. Hence, the maximum voltage for the output is determined by the resistor network on the FB pin.

If the analog voltage tracking is used to start-up the converter voltage a change at the mode pin from high to low or low to high will indicate the logic that the soft-start is completed.