Electronics > Beginners

How do I change output Voltage on this SMPS

(1/2) > >>

FriedMule:
I have found a PWM SMPS circuit in the Micro-cap spice program, it uses some sort of generic PWMVM chip. I have tried to change values on evry component but it keeps outputting 16V.
What chip shal I try to change the PWMVM with and what component combination will change the output Voltage?
Thanks in advance:-)

MagicSmoker:
Look at the voltage on the FB pin during steady state and then change the ratio of Rupper to Rlower to change the output voltage. Note that an isolated flyback like this can accommodate a fairly wide range of output voltage without changing the turns ratio of the transformer, but at some point you will have to change it.

Also note that changing Rupper affects the frequency compensation (but so does changing the output voltage - as we Yanks say, "you can't win for losing").

FriedMule:

--- Quote from: MagicSmoker on January 20, 2020, 10:54:27 pm ---Look at the voltage on the FB pin during steady state and then change the ratio of Rupper to Rlower to change the output voltage. Note that an isolated flyback like this can accommodate a fairly wide range of output voltage without changing the turns ratio of the transformer, but at some point you will have to change it.

Also note that changing Rupper affects the frequency compensation (but so does changing the output voltage - as we Yanks say, "you can't win for losing").

--- End quote ---
Sorry for my slow answer, but I was trying to make sure that it was not me who just made a stupid mistake. But for some reason nothing helps, so I have decided to ask all of you about a different design of a power supply.

I have looked for sollutions on google and other plases but I am not sure if any of them meets these criteria:
Ac pwm flyback buck smps 220V-240V AC in 5V-10V 1A-2A DC out

I do not need the rectifier part, just the AC-DC part and the PSU do not have to be variable. All I need is the possibility to change some resistor values to change the voltage..

Please if you have or can point toward a schematic, it would be extremely helpful:-)

Gyro:
Hopefully you're just using that circuit as a simulation learning example.

You cannot use it in practice because it doesn't have galvanic isolation between the 220-240V AC input and the output (due to the feedback network).

Just checking.

FriedMule:

--- Quote from: Gyro on January 22, 2020, 09:20:02 am ---Hopefully you're just using that circuit as a simulation learning example.

You cannot use it in practice because it doesn't have galvanic isolation between the 220-240V AC input and the output (due to the feedback network).

Just checking.

--- End quote ---
Yes for the moment, but I hope to end up making the unit.
About the feedback, I think I have seen where a feedback were made via an optocoupler?

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod