Roman Black Regulator doesn't work in LTspice???

frosty said:

Hero999 are you still around, need to ask a question about black reg

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Hero9999 doesn't post here anymore. But why ask him when the inventor is an active member?

Sorry Frosty I only just saw this post. I do not normally look in the "Circuit Simulation & PCB Design" section of the forum.

For 8.4v input -> 6.8v 0.9A output I think a SMPS (which includes my regulator) is NOT a good choice.

You only have 1.6v headroom between input and output and you will be lucky to get an efficiency of about 80% with these voltages, so you will have figures similar to this;
input = 8.4v 0.91A = 7.65W
output = 6.8v 0.90A = 6.12W

So you have no benefit at all from using a SMPS. I would suggest you use a linear regulator which will still give you the same 0.9A in and 0.9A out.

Google for "low drop out adjustable regulator" or start a post in the electronics projects forum with the title "How to build 6.8v 1A low dropout regulator?"

I hope that helps!