Buck voltage regulator with fixed PWM. If left alone to run, you will see that the capacitor current (red) will increase with the inductor current (blue). As the cap fills, the capacitor current will fall and the LED current (orange) will start to rise. Once the cap has filled up sufficiently, the pulses will center around 0mA and most all of the current will flow through the LED at a more stable level. Green is the diode current and is shown to visualize where the "extra" current comes from. Since SMPSs have a switch that turn off the circuit for a given period, the current going though the inductor has to come from somewhere. That somewhere is the diode.
Have fun!!
