I have a design with TOP247Y (already a bit older) where a small percentage of power supplies shows start up problems. In several documents a soft finish capacitor has been discussed. There are basically two variants. The basic one consists of just a capacitor which can range from 10 uF to 47 uF across TL431 (pins 3 and 2), see for example DI-41 (Design Idea 41). A more extended version adds a diode in series with the capacitor, and a resistor to created a discharge path. Once the capacitor is charged, the diode kind of isolates the capacitor from the circuit. See for example DI-43.
Is it possible that the basic circuit with just one capacitor can cause stability issues? What are the considerations to choose either the basic version or the more extended version?
Thanks and regards,