In SMPS there are two sources of loss: parasitics, and the controller. Usually, the load consumes more power than the controller, and the parasitic losses dominate. I have the opposite situation. I have a buck converter with a load of 50mW, input voltage of 5V and output voltage of 1V. My question is: what is the best topology that minimizes the controller current consumption? Assume that the dynamic performance is not important.
My current solution is 1 comparator + 1 opamp for a current source in order to get accurate hysteresis implementing a bang-bang controller. Is there anything better?
I should also point out that a 200mW controller will give you the same performance as a linear regulator. Since the controller needs to be powered by the input, this give an upper current consumption bound of 40mA.