Other Parts Discussed in Thread: LM73605, TPS54424, TPS54824
Hello,
I have integrated an LM21305 into my design. The idea is that I use a digital potentiometer to adjust the voltage into a resistive filament. The idea is as the filament warms and becomes more resitive I can increase the voltage to apply more power.
I am doing this by replacing RFB2 with a 1Kto10K digital potentiometer. I put this regulator in this configuration on my board and it does not work.
I purchased an evaluation board and with the same potentiomenter I can run all the way from 1V up to 11V with perfect 4A of output current in all cases.
Clearly I have a layout issue on my board I need to resolve, which I am able to do.
The question I have is am I wasting my time? The datasheet and worksheets make it sound like the device really only wants up to 5V VOUT and what I am trying to do (up to 11V) is not recommended? I don't want to spend all the time doing this if it is just going to break.
I have been running 11V/4A out of the evaluation board for an hour now and the device is staying pretty cool. Do you think I am ok running the device like this or am I going to have problems? The datasheet is not clear on the recommended output voltage range, I assume as a buck regulator it is ok up to its VIN right?
Thanks,
-Chris