Electronics > Beginners
Mains Supply options for diy (semi-professional) electronics
csheldon:
Hi all,
I wanted to know what is the common approach and best option when trying to design professional consumer electronics that need to work
on mains supply voltage. it is low power supply, say to around 100-200mA of secondary current (usually some mcu's and peripherals).
Problem with mains transformers + graetz + linear regulator is that it is relatively heavy and bulky.
SMPS is a potentially good option, but where to get SMD SMPS transformers? what IC's to use?
What is the ussual approach to this problem when designing diy (semi-proffessional to professional devices)
dmills:
The usual solution is to use an external off the shelf power supply module, makes all the mains safety certification pain go away.
I would be very reluctant to bother designing my own off line switcher for a product, especially for something jellybean like a micro plus peripherals sort of thing, the costs of certifying it for every interesting market would be such that just buying an off the shelf line lump is highly attractive (And if 5V @ 500mA will do you then, USB?).
Even if I was designing something that needed an internal power supply, I would still be thinking in terms of a brought in module, Meanwell IRM series or whatever, problem solved, onto more interesting things...
If you really wanted to do your own flyback for some reason then Coilcraft, Wurth and others have transformers for specific chipsets, but it is seldom worth the pain.
Regards, Dan.
jeroen79:
Seconded.
Either use an external powersupply or some drop in module.
You can simply solder these onto the PCB.
Benta:
It's a really good idea to use a universal SMPS, meaning it should have an input voltage range of 90...265 VAC.
GeoffreyF:
For a consumer product the design decisions have a very great deal to do with insurance liability. To manage that risk, the entire "box" into which mains go has to be certified safe by an organization such as UL, CE, ETL. The most expedient thing is to OEM a device that has these certifications and delivers low voltages to the product. Certifications are often needed for that product because of rechargeable batteries and so forth, but they are simpler to achieve.
The certifications are very strict for something with mains voltage if the consumer might be holding or touching the thing while it is plugged in.
Over the years, the requirements for certification have become more strict.
For someone who is building something for use by others, in the home or someone else's home, it's also wise to build it around a certified power supply that delivers low voltage from the mains. You could be liable for injury as well.
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