Either can work but the second version is better...why add extra load on output of the 5V converter?Steve
If you mean it is difficult to adjust the voltage but it stays consistent once you take your screwdriver off the potentiometer, that is a problem with the quality of the potentiometer.The main concern when cascading buck converters is their efficiency - If you feed a converter with an efficiency of 80% into another with an efficiency of 80%, your overall efficiency is 64%. And they are generally more efficient the higher the input voltage (and the higher the output voltage).If they interact, you may need more capacitance on the power input. What 12 V supply is it anyway?
Usually efficiency is greater when input and output voltages are close to each other, so daisy-chainingis likely to mean each converter is being more efficient than with independant converters, but that won't translate to overall efficiency unless the lower voltages are using much less power that the higher voltages.So perhaps my take is use a direct conversion for anything using significant power, daisy chain the lowerpower converters as is convenient.Most complex electronics devices tend to have a cascade of supply converters, an advantage is you get repeatable and well defined power-up sequencing.And you can cascade a buck converter with a linear regulator to optimize efficiency and get low-noisesupply as well - so for instance with 12V in, buck convert to 5V, linear regulate the 5V down to a clean 3.3V analog rail. Instead of dropping 8.7V in a linear regulator, you only drop 1.7V, so less waste,less heat to get rid of, and no switching noise on the 3.3V rail... The 5V supply may be wanted anyway.