There are commercially-produced flashlights that use SMPS and continuous dimming. As they're all managed by microcontrollers, I'm sure it's actually hundreds or

There are commercially-produced flashlights that use SMPS and continuous dimming. As they're all managed by microcontrollers, I'm sure it's actually hundreds or thousands of discrete steps. > At some point I'll find out why LEDs need constant current. There are flashlights that work by connecting a Li-ion battery to an LED through a FET that can use PWM to dim it. This will deliver all the power the battery is capable of providing at a given point on the LED's forward voltage curve. If that sounds like a good way to burn out components, it... can be. Everything needs to be fairly robust. These flashlights do not have constant brightness. Even in lower modes, output tracks battery voltage. Strictly speaking, however, it demonstrates that it's possible to operate LEDs without constant current. Forward voltage drops a bit as temperature increases though, so LEDs are "greedy" and will essentially take all the current available as long as there's sufficient voltage. At some point, this will let the magic smoke out. FET drivers in flashlights only work because the voltage range of the battery and LED overlap, battery voltage sags when it gets a heavy load on it, and some LEDs can handle a lot more current than the datasheet says for a few minutes at a time. None of these things are valid for mains-powered lighting, except that with sufficient heatsinking, many LEDs can be overdriven at a modest cost to longevity.