I am developing a PID controller to use in a buck converter (13V->5V). The problem is how to physically implement the signal which acts as the reference voltage and generate the error signal. I don't have a 5V DC voltage source to use as the reference (otherwise the buck converter would be useless because I would be able to simply use this 5V source).

I've heard something about using a DAC to implement this, but I am not sure how it should work.

Thank you


The analog way to do it is to use any voltage reference circuit to get a reference signal from the 13V side. The easiest idea to go for is a zener voltage, maybe even an adjustable one (like the LM431). You don't need to power anything from this zener voltage, you just need to produce an error signal. Therefore your buck converter is still useful (to actually deliver power to a load).


simulate this circuit – Schematic created using CircuitLab


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