Tool/software: WEBENCH® Design Tools
Hi,
I've designed a simple LM3481-based boost power supply circuit in Webench with the following parameters:
Vin: 14-20VDC
Vout: 24VDC
Iout: 3A (max)
I then tweaked various parts' values of the original design - within the specified limits - to match more commonly found parts.
The final design can be found here.
(The said design is also attached below in pdf format in case the above link doesn't work)
I subsequently move on to breadboard the circuit with a good quality 18.5V/6A power supply for Vin, but instead of the expected 24VDC output, only got the same voltage as the input, that is, ~18.5V (either with or without a load).
It's worth noting that I only used quality parts (resistors/caps/etc.) and made sure the resistor values precisely match those in the schematics. I also checked all the connections and they looked ok.
In case one of the original parts was a dud, I subsequently re-built the entire circuit with new parts (including a new LM3481 and a different good quality 16VDC power supply), but got the exact same result, that is, Vout equal to Vin, or in this case: 16VDC.
Given the repeated result, it seems likely to me that the problem isn't in the parts or the build, but rather somewhere in the design itself. My guess is that the switcher isn't working at all and that's why the input & output are the same, but that's only a guess (unfortunately, I don't have access to anything beyond a simple multimeter so I can't offer oscilloscope data or similar).
Having spent a fair amount of time and money on this design so far, I'm rather exasperated by the poor outcome and was hoping someone would be able to shed light on why this circuit isn't working.
Many thanks in advance,
Nadav
