The soft-start feature is used to prevent inrush current impacting the TPS541620 and its supply when power is first applied. Soft start is achieved by slowly ramping up the target regulation voltage when the device is first enabled or powered up. For dual-output applications, the external soft start is disabled and the outputs turn on with an internally-set soft start time of 1 ms. In this situation, leave the SS pin floating. The external soft start is enabled when the device is configured in multi-phase operation. Multi-phase applications that deliver high load current can have a large amount of capacitance at the output. The soft-start time for such applications can be extended by connecting an external capacitor C_SS from the SS pin to AGND to make sure there is no sudden current surge. Extended soft-start time further reduces the supply current required to charge up output capacitors and supply any output loading. An internal current source (I_{Ct_SS} = 2 μA) charges C_SS and generates a ramp from 0 V to V_FB to control the ramp-up rate of the output voltage. The soft-start capacitor C_SS is discharged through an internal FET of 600-Ω resistance when V_OUT is shut down by fault protection or EN low. The total time required to discharge the soft-start capacitor completely is 500 µs. When a large value of C_SS is connected and EN is toggled low only for a short period of time, C_SS may not be fully discharged. The next soft-start ramp follows the internal soft-start ramp before reaching the leftover voltage on C_SS and then follows the ramp programmed by C_SS.