Hi,
I'm trying to design a boost converter with a variable output. My Vin wil be given by three AA cells, my output has to be a maximum of 40V@0.1A.
I made a sizing in webench and it recommended me to use a LM3478. I'm going to prototype the circuit and only change the LM3478 by a LM3481. The other components are going to be the same. Is that correct? or should i tweak some components value when switching from LM3478 to LM3481?
What i would like to do next is to be able to control the output voltage with a uC. It should vary from Vin to 40V. I would use a digital potentiometer instead of a resistance in the feedback loop but of course, i can't find one that will work for such a high voltage.
My idea would be, in the feedback loop, to divide by ten the output voltage with two resistances, then use a digital potentiometer and an op amp to obtain the correct value on the FB pin. It should work theoretically, but i don't know if it's a good idea to put some components in the FB loop. If i take a lot of care when designing the pcb to reduce the size of the FB loop, could it work? Do you have any other idea or reference design to do something similar?
Thanks,
