How do I mitigate the input overshoot when plugging in a power source? I want to plug in 24V to the TPS54231 and get 5V out.
I believe my root problem is the charging input caps. With just a 0.1uF ceramic cap and 24V from a power supply, the overshoot peaks at 44V!
I do not get overshoot with a 47uF aluminum electrolytic capacitor. I assume this is due to the high ESR slowing the charge.
The overshoot is only 40V with long runs of cable (500+ ft 18 guage). I think the resistance of the cable slows the charging and diminishes the overshoot.
The overshoot peaks at 26.4V with a 3Ω resistor at the input, but my application can take up to 1.3A. That's a wasted 5W burning at the input! (plus whatever is burned off in the cable). I would like to set the enable pin to turn on at 20V. (20 > 24-5). This point corresponds to the long cable run. 500 ft of 18 gauge is ~3Ω. Maybe the overshoot is still dramatic because of the cable's inductance. The resistance diminishing overshoot is a bit greater than the inductance adding to it???
I have tried a variety of ferrite beads on the input instead of resistors, but without much impact. An inductor would limit the input rush, but inductance is also the thing I think is causing the overshoot in the first place. An RC circuit doesn't overshoot buy itself.
