Understanding RLC series circuit fed with a square wave

I'm simulating a RLC series circuit fed with a 60Hz 3.3V square wave coming from a microcontroller. The inductor series resistor is 100 ohms, so the total R= 110 ohms. According to the simulation, the peak current is about 17 mA for those values. I would like to do the proper math to get that result. It looks like the circuit is overdamped, R^2 > 4L/C. But I don't come up with those 17 mA peak. How do I calculate it? If you have any book or resource that helps me understand this better, I will appreciate it. Thanks.

• Would you mind showing us some of what you have calculated and how you approached it? Or is this a case where you already know you have so few clues, that sharing would be pointless? – jonk Apr 6 '20 at 1:08
• @jonk I have few clues actually, so sharing is pointless. Somehow this is something I'm trying by myself (no homework). Something that just came to my mind and I want to understand. I have a micro, if I generate a square wave from it and feed this to an RLC series circuit, how do I calculate the inductor current? Or at least how I explain the graph above. – user115094 Apr 6 '20 at 5:44
• I believe you when you say you have some clues. I don't believe that having them means "sharing is pointless," though. Quite the opposite, in fact. Since you have clues, you should be able to show your work. That will go a long way in helping us first to see how you approach solving it and then possibly where we might suggest where an assumption or a logical step was made incorrectly. Otherwise, this all just boils down to one of us offering you how we'd do it. Since there several ways, maybe as many as people who might help here, I'm not sure how that's better. You won't add anything? – jonk Apr 6 '20 at 6:21
• I just used LTspice and your circuit and included the fact that the inductor has an internal series resistance of $100\:\Omega$. I set the rise and fall times to 1 nanosecond to square up the so-called "square wave" and find quite different peak currents (more like those I hand calculated.) This just goes that much further in asking you what you did calculate. Perhaps it's right! The only thing I can tell you right now is that your LTspice plot isn't giving you correct values. Why don't you also plot the pulse wave, too? – jonk Apr 6 '20 at 6:39
• Well, I cannot explain why we get different results if we have the same values. Anyway, I plan to test this in the real world, but I want to understand how to choose/calculate the components value to give a certain amount of AC current pulse. – user115094 Apr 6 '20 at 6:44