8.3.1 Soft Start-Up

Soft-start circuitry is integrated into the device to avoid a high inrush current during start-up. After the device is enabled, the voltage at FB pin ramps up to the reference voltage in 32 steps — each step takes 213 μs. This ensures that the output voltage rises slowly to reduce the input current. Additionally, for the first 5 msec after the COMP voltage ramps, the current limit of the switch is set to half of the normal current limit specification. During this period, the input current is kept below 700 mA (typical). These two features ensure smooth start-up and minimize the inrush current (see Figure 6).