I'm looking at powering an embedded board PC using a 12V PSU and I'm having some trouble due to inrush current. The board draws 5A for about 1ms on startup and unfortunately this trips my PSU's overcurrent protection. I did some research online and it looks like I can get an inrush current limiter from Digikey (http://www.digikey.com/product-search/en/circuit-protection/inrush-current-limiters-icl/656273).
My question is will these inrush current limiters work for a DC output, or is there a better way around this? I've only seen people talk about using the inrush limiters at the input side of AC-DC converters, although some places mention it can be used in DC scenarios, but with no examples.
If these inrush current limiters will work for my purpose, do I just pick one with a steady state max current that's lower than my PSU's maximum output, and pick one with an R@25c value that gives me an acceptable current limit at 12V?
Best Answer
They work on dc just fine and your reasoning about choosing the correct one is also sound. You probably know this but inside is basically a thermistor that has a negative temperature coefficient so when cold they will exhibit higher electrical resistance and reduce inrush current. They rapidly warm and the resistance drops.
You might also try inserting the equivalent to the warm resistance in series. This might be enough on it's own.
One caution; if you switch power off then restore it too quickly you may still get an inrush problem because the device hasn't cooled down sufficiently. There are mosfet circuits that do the same thing too.