10.18 Slow Start (SS/TR)

Connecting the STSEL pin to AGND and leaving SS/TR pin open enables the internal SS capacitor with a slow-start interval of approximately 1.2 ms. Adding additional capacitance between the SS pin and AGND increases the slow-start time. Increasing the slow-start time reduces inrush current seen by the input source and reduce the current seen by the device when charging the output capacitors. To avoid the activation of current limit and ensure proper start-up, the SS capacitor can need to be increased when operating near the maximum output capacitance limit.

Figure 29 shows an additional SS capacitor connected to the SS/TR pin and the STSEL pin connected to AGND. See Table 6 for SS capacitor values and timing interval.

Figure 29. Slow-Start Capacitor (C_SS) and STSEL Connection