SLVSDT1C July 2017 – June 2020 TPSM82480
The internal soft-start circuit controls the output voltage slope during startup. This avoids excessive inrush current and provides an adjustable controlled output-voltage rise time. The soft-start period also prevents unwanted voltage drop from high impedance power sources or batteries.
When EN is set to start device operation, the device starts switching after a delay of typically 200 µs and VOUT rises with a slope, controlled by the external capacitor which is connected to the SS/TR pin (soft start). Leaving the SS/TR pin floating or connecting to VIN provides internally set fastest startup with a soft-start slope of approxiimately 80 µs. See Application Curves for typical startup operation.
The device can start into a pre-biased output. In this case, the device starts switching, only when the internal set point for VOUT increases above the pre-biased voltage level.