KX36
Junior Member level 2
Hi all,
I am trying to design a switch mode power supply to run off mains supply of 230Vac with a variable output voltage up to about 25Vdc set by a separate microcontroller. I'm not an electrical engineer and this is the first time I've done anything like this, I'm learning as I go along, but I'm not in a rush and this is all theory right now for me.
Here's what I need from it:
Offline SMPS, running on 230Vac mains supply
It would have to be an isolated topology
It would be probably around medium power (up to 100W load)
The output voltage has to be able to be adjusted over a wide range, from near 0V up to around 25V, by the output of a microcontroller (analog or digital output).
I want to keep it as simple as possible while maintaining function and stability (don't we all).
I have been looking at some application notes and datasheets for PWM controllers and I think that an isolated flyback circuit could work but I don't know how to control it from a microcontroller.
**broken link removed**
Here's a simple draft of a schematic based on this application note: https://www.ti.com/lit/an/slua143/slua143.pdf
The opto-isolator circuit is from this application note: https://www.fairchildsemi.com/an/AN/AN-400A.pdf
As you can probably see, I just patched it together from these documents to get something to start with; it's not a finished circuit and I doubt it is complete. I'm certainly not comitted to using all or any of it.
What I want to know is what is a good way of achieving my aim of having a microcontroller control the output voltage of a circuit such as this. Can someone please give me a push in the right direction.
Cheers,
Matt
I am trying to design a switch mode power supply to run off mains supply of 230Vac with a variable output voltage up to about 25Vdc set by a separate microcontroller. I'm not an electrical engineer and this is the first time I've done anything like this, I'm learning as I go along, but I'm not in a rush and this is all theory right now for me.
Here's what I need from it:
Offline SMPS, running on 230Vac mains supply
It would have to be an isolated topology
It would be probably around medium power (up to 100W load)
The output voltage has to be able to be adjusted over a wide range, from near 0V up to around 25V, by the output of a microcontroller (analog or digital output).
I want to keep it as simple as possible while maintaining function and stability (don't we all).
I have been looking at some application notes and datasheets for PWM controllers and I think that an isolated flyback circuit could work but I don't know how to control it from a microcontroller.
**broken link removed**
Here's a simple draft of a schematic based on this application note: https://www.ti.com/lit/an/slua143/slua143.pdf
The opto-isolator circuit is from this application note: https://www.fairchildsemi.com/an/AN/AN-400A.pdf
As you can probably see, I just patched it together from these documents to get something to start with; it's not a finished circuit and I doubt it is complete. I'm certainly not comitted to using all or any of it.
What I want to know is what is a good way of achieving my aim of having a microcontroller control the output voltage of a circuit such as this. Can someone please give me a push in the right direction.
Cheers,
Matt