I'm not looking to get torn apart, just looking for a hand.
I can't remember exactly how to calculate the RMS Current required from the output capacitors or a Buck-Boost power supply and I was hoping to get some help. If someone could show me how its done that would be awesome but equations will help as well. I have listed some specs below if anyone wanted to try doing some quick math out, I can post more if needed as well.
I chose the following Inductor and for now I chose to use 4 of the following Capacitors just in my preliminary design, I will change/add/subtract them depending on the calculations. I just need to know what the bulk capacitors will have to supply for current @100kHz, the other caps are just for fine tuning later on.(Inductor Selected: IHLP3232DZER2R2M01, Capacitors Selected: TCJD476M020R0055)
Iout(MAX) = 5A, Vout = 13.6V, Vripple = ±.1V, Cout(4@47uF) = 188uF, CAP_ESR(@100kHz) = 55mΩ, CAP_DF(MAX) = 6, Fsw = 100kHz, Vin(MIN) = 4V, Vin(MAX) = 20V
Answer
Looks like you're talking about a non-inverting buck-boost, so for the output caps the boost mode is the worst case.
So using the minimum input voltage and maximum output current follow the steps given HERE to calculate the ripple current in the capacitors.
You can also download a power stage calculator that can do the calculations for you like the following one from TI: Power Stage Designer
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