# 12V to 48V power supply of up to 16A

Discussion in 'Power Electronics' started by crazybuoy, Oct 12, 2016.

1. ### crazybuoy Thread Starter Active Member

Sep 19, 2010
77
0
I have 12V , 16A from ATX power supply by collecting all yellow cables and same number of black cables on the other side.

I want to convert it to 20, 25, 30.....48V and the input current (16A) should not be decreased, it means, there should be 12-16A with output voltage.

I have searched schematics a lot but could not decide which one to use.

Please suggest me any circuit as small as possible.

2. ### wayneh Expert

Sep 9, 2010
13,423
4,264
No such thing exists. You cannot create power. At best you can convert voltages and currents with minimal losses of power.

Feb 20, 2016
486
125
wayneh is correct. You cannot create extra power.
In simple terms, If you have a 12V 16A supply, it is able to supply 12V x 16A = 192 Watts.
You are wanting to convert the 12V to 48V. There are switch mode boost circuits that will do it but that will only give you 4A. (192/48=4).
Likewise..
192/20=9.6W
192/25=7.7A
192/30=6.4A
As you see, while the voltage goes up, the current goes down.
A 48V 16A supply needs to be rated at about 770Watts.

4. ### crazybuoy Thread Starter Active Member

Sep 19, 2010
77
0
Got the point.

At 48V, 3-4A is enough for me. You can suggest any Switch Mode Boost Circuit as small as possible. I also need variable voltage between 12-48.

Thanks

Feb 20, 2016
486
125
6. ### crazybuoy Thread Starter Active Member

Sep 19, 2010
77
0
I want to create a similar circuit for this purpose on my own. Please suggest one or two.

7. ### crazybuoy Thread Starter Active Member

Sep 19, 2010
77
0
Please check this variable power supply circuit.

Can it provide output of 48V, 3-4A when using 12V 16A as input?

• ###### 100 amp variable power supply circuit.png
File size:
263.2 KB
Views:
12

Feb 20, 2016
486
125
No. That circuit cannot.
That is a very simple circuit that can only drop the voltage and it is unregulated. Also it would waste a a lot of power as heat.
What you are trying to do is not as simple. Look at ..
https://en.wikipedia.org/wiki/Boost_converter

You will need an inductor that is switched to create the voltage boost and a control circuit plus quite a bit of other stuff.
All this is possible to make but if you are new to electronics it is quite a challenge. Think lots of smoke!

Here are some app note to start the calculations...
www.ti.com/lit/an/slva372c/slva372c.pdf
www.ti.com/lit/an/snva731/snva731.pdf

http://www.ti.com/analog/docs/analo...&rootFamilyId=64&familyId=752&docCategoryId=1

www.linear.com/docs/26920

This is just from a Google search and I've not looked into them all as yet.

This is a good project for you to try but don't hook anything of value on as a load until you have it well working and stable. There are a lot of traps to building your own switch mode power supplies, and more so as the power goes up.

Have a search on Texas Instruments site, Linear technology, Maxim and ST amongst others.

9. ### tcmtech Distinguished Member

Nov 4, 2013
2,684
2,444
You will be time and money ahead to just buy a regular 48 volt SMPS unit and modify its feedback loop so it can be adjusted to putout lower voltages.

10. ### crazybuoy Thread Starter Active Member

Sep 19, 2010
77
0
Hi,

I found this simple circuit to convert 12V to 48V. Is there any change possible in circuit to make it VARIABLE between 12-48.

Thanks

11. ### Dodgydave AAC Fanatic!

Jun 22, 2012
6,406
1,016
No, that circuit is a Flyback oscillator with a pulsed output.

You're better getting a 50V switch mode psu, and buck converter chip like Lm2596.