I'm stuck between choosing to use either a buck converter or a LDO voltage regulator for my heated glove project. The voltage regulator's function in question will be to power the microcontroller. What I am having trouble deciding on is which is better for low power applications. Low power as in powering a microcontroller that draws only a few uA of current. So in any case, which would be better for my project: a buck converter or a low quiescent LDO? Or does it not matter in this case.
Voltage Regulator: LM2936MPX-5.0/NOPB
Buck Converter: LMR14203XMK/NOPB
Best Answer
as your micro controller is only drawing such a tiny amount of power, an LDO with a low quiescent current, ideally lower than your microcontroller, will likely end up more efficient, most inductor based switching converters struggle at very low loads,
e.g. the LDO you linked draws 15uA at idle, so your power wasted is (the supply current of your micro * The voltage your dropping) + (15uA * the input voltage)
The switching converter has a 1350uA quiescent current, however you can see on the graphs used that the efficiency of the converter falls off to nothing at low currents, so under ideal conditions, you will be burning atleast (9 times the supply current of the micro * the output voltage) + (1350uA * input voltage)
As an alternative there are switched capacitor buck regulators, this would sit fairly close to the LDO for sub 1mA supply currents and a low voltage drop, whether it is better or worse would require knowing exactly how much current you need and how large the voltage drop is.
edit: deceptive idle current on the switching regulator,