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Trimming output on Switched mode power supply?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Trimming output on Switched mode power supply?
okelk
Hi!

Does anybody has experience with trimming the output voltage on a Switched mode power supply?
The datasheet of the Mean Well DKA30 ( https://www.tme.eu/en/Document/d1ee267692ad83ea5a9d49cbdf4bda10/dka30- spec.pdf ) says that the output can be trimmed +/-10%.

There's also this graphic:


Unfortunately that doesn't really help me that are the values of that trimmers and what trimmer is supposed to do what and why?

..to provide some context, the goal is to either trim the 12V model 10% up, or the 15V model 10% down and use it with a LDO regulator.
davebr
okelk wrote:
Hi!

Does anybody has experience with trimming the output voltage on a Switched mode power supply?
The datasheet of the Mean Well DKA30 ( https://www.tme.eu/en/Document/d1ee267692ad83ea5a9d49cbdf4bda10/dka30- spec.pdf ) says that the output can be trimmed +/-10%.

Unfortunately that doesn't really help me that are the values of that trimmers and what trimmer is supposed to do what and why?

I have no experience with trimming that model. However, here is how I interpret that drawing:

It is three separate examples. A resistor connected between the negative output terminal and trim will increase the voltage. A resistor connected between the positive output terminal and trim will decrease the voltage. To make it adjustable, connect a 20K trimmer between the positive and negative terminal and connect the wiper to trim.

Dave
okelk
davebr wrote:
okelk wrote:
Hi!

Does anybody has experience with trimming the output voltage on a Switched mode power supply?
The datasheet of the Mean Well DKA30 ( https://www.tme.eu/en/Document/d1ee267692ad83ea5a9d49cbdf4bda10/dka30- spec.pdf ) says that the output can be trimmed +/-10%.

Unfortunately that doesn't really help me that are the values of that trimmers and what trimmer is supposed to do what and why?

I have no experience with trimming that model. However, here is how I interpret that drawing:

It is three separate examples. A resistor connected between the negative output terminal and trim will increase the voltage. A resistor connected between the positive output terminal and trim will decrease the voltage. To make it adjustable, connect a 20K trimmer between the positive and negative terminal and connect the wiper to trim.

Dave


Oh thanks!
If you think about it as 3 different examples, it suddenly makes much more sense...
...still..I think It's kind of weird that there is not more information on how to calculate a trimming resistor....but ok.
fuzzbass
My guess is the value of the fixed resistors is dependent on the load.
mskala
If it is just detecting the voltage applied to the trim input, then the value of the resistors won't matter very much. Note that if you use the potentiometer then when it's at the top or bottom of the range, that is equivalent to just shorting the trim input directly to one of the rails as far as what's seen by the trim input.
vonkhades
okelk
did you manage to make it work with the suggested configuration?
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