The integrated soft-start circuit prevents input inrush current impacting the LMR51635 and the input power supply. Soft start is achieved by slowly ramping up the internal reference voltage when the device is first enabled or powered up. The typical soft-start time is 4ms.

The LMR51635 also employs overcurrent protection blanking time, T_{OCP_BLK} (8ms typical), at the beginning of power up. Without this feature, in applications with a large amount of output capacitors and high V_OUT, the inrush current is large enough to trigger the current-limit protection, which can cause a false start as the device enters into hiccup mode. This action results in a continuous recycling of soft start without raising up to the programmed output voltage. The LMR51635 is able to charge the output capacitor to the programmed V_OUT by controlling the average inductor current during the start-up sequence in the blanking time, T_{OCP_BLK}.