How much would soft-start (a slowly increasing duty cycle?) help this simulation?
Some input capacitance, a slight delay or a current sense circuit might help just as much if not more?
The controller would wait until the input capacitor voltage exceeded some "turn-on" threshold. At this point Vout would be fairly close to Vin. Since a boost supply requires more input current than output, the input capacitor is not uncommonly larger.. making the above even more so. This is all assuming there's zero delay in demand. A little delay brings Vin and Vout even closer. Since the current sense circuit prevents
the switch from increasing inductor current beyond ~Ipeak, it alone would really help to eliminate this issue, no?
I'm learning quite a bit just talking about this. Thank you. I suppose the general idea to pull from this simulation is that you don't want the output capacitance of a boost supply too large if you need your output to turn on instantly. Especially if you do not have a current sense circuit. It's a concept I never really thought about, but could see how it would really ruin your day.
Luckily in my application the batteries are installed and the LEDs are not lit for at least one switch debounce period. By that time the ouput capacitor should be fully charged. I do not have a current sense circuit to protect the inductor from current build up, but I am planning on an additional inline circuit for linear current limiting after the output cap. That should cover all bases?
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It would be quite a mistake to assume that the current limiting circuit inside a monolithic regulator works that fast. Also, the current limit value isn't exactly the maximum datasheet current. I have a circuit right now that uses a 175mA boost converter. The load pulses from about 140mA to about 190mA and the current limit NEVER kicks in during normal operation. These load spikes last about 500ms or longer. I'm actually limited more by the thermal cutoff in the device than by the current limit circuit.
So no, inrush current will not be properly dealt with by the current limit circuit, hence the soft start circuit.
Would this be more of a comment on controller tolerances or some specific concept the soft-start helps with?