Buck-Linear Mashup

137

02:20:58

A Buck-Linear regulator (also known as a linear regulator with switching preregulator) combines the best of both worlds (efficiency, stability). I can't seem to dampen the filter enough though. I either have to increase the dampening resistance to a considerably unacceptable value, or make the filter with a lower corner frequency - at which moment EC stops working 🤣

P. S. The 1ohm resistor decreases the efficiency a lot. Need some help stabilising the filter... 

published 6 years ago

kiani

6 years ago

I increased 5us to 50 us.. Pluscadded some hysterisis to the opamp (comparator) deriving the Fet { 100k + f/b}. Then it all seems happy.

thebugger

6 years ago

Yeah, I thought of the hysteresis, but I don't think we need it, cuz this is not a self-running system, so It doesn't need hysteresis for stability. You may add some hysteresis (470k over 1k for instance, just to force the comparator to always be in switching mode, and never enter linear mode, but I think it is a bit redundant. Good idea, and It makes sense from technical perspective, but since this is just a prototype, I might dwell on it further in a future version.

PrathikP

6 years ago

If a circuit with op amps crashes on me, i add 100nF caps between all op amp inputs and ground, and that usually does the trick for me.

PrathikP

6 years ago

Take this circuit for example http://everycircuit.com/circuit/5589307763720192 without those caps, my sim crashes.

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