Author Topic: 230V AC to 12V 3A conversion without transformer ?.  (Read 1597 times)

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Offline sangarTopic starter

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230V AC to 12V 3A conversion without transformer ?.
« on: February 11, 2019, 05:12:26 am »
Hello All,

I need to design a power block to supply my processor board and it should be a compact one...The input will be 230V AC and output to be expected is 12V 3A. I have seen some reference design from Monolithic systems for this, it seems that >10W needs a transformer...If it is right, what are the reasons which require a transformer for >10W supply design...Please suggest.

Thanks,
Sangar


 
 

Online Ian.M

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #1 on: February 11, 2019, 05:22:51 am »
Safety + capacitive droppers have horrible power factor and no load dissipation greater than their max output power.

Do what everyone else does and buy in a SMPSU power 'brick' with the required output voltage and current and all the safety approvals you need for your intended markets.   A 12V 4.1A (50W) SMPSU should be a commodity item as that voltage is commonly used in LED and Halogen lighting systems.
« Last Edit: February 11, 2019, 06:15:06 am by Ian.M »
 

Offline BravoV

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #2 on: February 11, 2019, 06:13:30 am »
Try Vicor.

Online Zero999

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #3 on: February 11, 2019, 10:06:10 am »
Safety + capacitive droppers have horrible power factor and no load dissipation greater than their max output power.

Do what everyone else does and buy in a SMPSU power 'brick' with the required output voltage and current and all the safety approvals you need for your intended markets.   A 12V 4.1A (50W) SMPSU should be a commodity item as that voltage is commonly used in LED and Halogen lighting systems.
Yes, typically a SMPS is used, which does have a transformer, but it works at a much higher frequency, than the mains, so can be a tiny fraction of the size of a bulky mains transformer.

Beware, lots of halogen lighting PSUs are merely transformers driven by a Royer oscillator. They're unsuitable for powering most electronic circuits from because they output 20kHz to 200kHz modulated by double the mains frequency and commonly have a minimum load current requirement.

Here's an application note, showing the typical schematic, for educational purposes.
https://www.st.com/content/ccc/resource/technical/document/application_note/e5/88/46/11/35/8c/4a/bf/CD00003902.pdf/files/CD00003902.pdf/jcr:content/translations/en.CD00003902.pdf

A 12V LED power supply designed for LED strip is a better option. It will output steady DC and a suited for most electronic circuits.
 
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Offline sangarTopic starter

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #4 on: February 11, 2019, 01:26:43 pm »
Hi All,

Thanks...Our requirement is that the power module to be designed should not exceed the board size of 50mm x 50mm and be bulky...As far as I searched, I couldn't find any power module which is within 50mm x 50mm...If one can design it in the given size, I am asking you to share the sources that guide me to design...

Thanks,
Muthu
 

Online Doctorandus_P

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #5 on: February 11, 2019, 03:32:12 pm »
Power scales with size.

Why generate 12V for a "processor board" ???
3V3, or maybe even 5V seems more appropriate.

When you look at Ali, "open frame" and "single output" seem to be good magic words for starters:
https://www.aliexpress.com/wholesale?SearchText=open+frame+50W
 

Offline alex-sh

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #6 on: February 14, 2019, 10:28:32 am »
Power scales with size.

Why generate 12V for a "processor board" ???
3V3, or maybe even 5V seems more appropriate.

When you look at Ali, "open frame" and "single output" seem to be good magic words for starters:
https://www.aliexpress.com/wholesale?SearchText=open+frame+50W

Did you try any of these Ali open frame PSUs? My biggest problem is ripple/noise and power for any processor board must be very clean.
 

Offline mariush

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Re: 230V AC to 12V 3A conversion without transformer ?.
« Reply #7 on: February 14, 2019, 10:43:22 am »
Why do you need 12v?
Do you need it just because you have a fan or you have a small number of components that need 12v? You may be able to use a step-up regulator on your board for those parts and use a lower voltage power supply otherwise?
Do you use linear regulators to get the voltages you want? If so, maybe you could change them for step-down/buck regulators and use a higher input voltage like 18v..24v for higher efficiency, and so you may not need 30w+ of power.

 
 


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