Recently the idea struck my mind, that I wanted to build a simple but useful emergency light which can run off of any USB port (the specific use case would be to power it from an USB power bank). For that I wanted to design a simple circuit that drives 25 white LEDs (3.2 V, typ.) in parallel.
The question I am facing now is how to achieve a simple design while not using 25 series resistors, as this is just wasteful and not space efficient, for me anyway, I just want to make it more clever somehow.
Is it enough to just step the 5 volts (from the USB) down to 3.2 volts using an off-the-shelf linear regulator like the LM317 and then connect all the LEDs to it in parallel or will the non-ideal characteristics of aforementioned spoil my plan?
I might be overthinking this, which is why I am asking if there might be a better, simpler or more efficient possibility to achieve what I want? :)