JAJSBH8G June 2010 – February 2018 TPS65251
PRODUCTION DATA.
The soft-start capacitor determines the minimum amount of time it will take for the output voltage to reach its nominal programmed value during power-up. This is useful if the output capacitance is very large and would require large amounts of current to quickly charge the capacitor to the output voltage level.
The soft-start capacitor value can be calculated using Equation 24. In this example, the converter’s soft-start time is 0.8 ms. In TPS65251, Iss is 5 µA and Vref is 0.8 V. From Equation 24, the soft-start capacitance is 5 nF. A standard 4.7-nF ceramic capacitor is chosen in this design. In this example, C16 is 4.7nF