would like to understand the Soft stat Capacitor scale for part TPS55340
Currently we have a 47nF based on the data sheet application design. But we don’t have an actual scale defining the soft start timing versus capacitance.
It seems that we need more capacitance to prevent in rush current… Would the application engineers be able to tell us the maximum capacitance recommended? Could they provide a reference scale?
Hi Marcio,
Can you give more details on the topology you are using TPS55340 with?
Based on the topology, the softstart implementation may change.
We have a good application note, that gives detailed explanations on softstarts in general and for different topologies:
https://www.ti.com/lit/an/snvaa44/snvaa44.pdf
If you questions is just about the calculation of the softstart time, the datasheet lists more details on this:
Based on the 6uA current source and the capacitor size, the time can be calculated until the 1.8V completion voltage is reached.
Best regards,
Niklas
