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Topic: DC-DC Buck Converter high current usage when idle (Read 4256 times) previous topic - next topic

aarg

I see. Well there's NO setup :)
DC-DC converter is connected to variable DC supply, output is not connected anywhere
Hmmm... some variable supplies have a current limit adjust. You would be surprised how often you can forget to turn it up.
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

bratan

Hmmm... some variable supplies have a current limit adjust. You would be surprised how often you can forget to turn it up.
You are correct mine has that :) But what does it have to do with high current draw from DC-DC converter? If I forgot to dial it up, it should've been lower not higher than normal, right?
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aarg

Sure. I'm just Holmesing it (when every possibility has been ruled out, the one that remains is the solution, however unlikely it may be). :)
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

bratan

Sure. I'm just Holmesing it (when every possibility has been ruled out, the one that remains is the solution, however unlikely it may be). :)
LOL I know what you mean, I do it a lot when desperate :)  Never helps directly, however usually gives me another idea in the process :)
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Martin-au

I know this is an old topic, but I just bought two of those, and got 40mA when idle as well. They also got quite warm. I've binned them.

6v6gt

#20
Sep 30, 2017, 01:19 pm Last Edit: Sep 30, 2017, 01:21 pm by 6v6gt Reason: added picture
I have two of these identical with the picture in the OP which I will be using to power filaments of VFD displays (c. 1 volt) at some time in the future. I guess it will be a couple of years before these see any use.

Anyway, I have tested both and the no load current is 0.7mA which is fine for my purpose.

What I did notice, however, that marking of the terminals on the rear is somewhat confusing. There are 2 input terminals and 2 output terminals (actually solder pads for header pins). The input pins appear to be marked correctly. However, both output pins are marked as having negative polarity !

I'm not going to try any permutations of wiring errors but that could be a plausible explanation for the high current consumption reported.


jayx

Old topic, but it still may be useful for someone.

I've had the same issue with them. Initially I've measured quiescent current (@Vout = 5V): Vin = 10V 45mA, Vin = 20V 30mA.

I've found that originally fitted inductors (4.7µH) are too low value, after replacing them I've measured:
Inductor 10µH  @Vin = 10V 8mA, @Vin = 20V 18mA
Inductor 22µH  @Vin = 10V 6mA, @Vin = 20V 7mA

And yes, one of the output terminal is marked incorrectly, but it's pretty obvious which one is which.

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