Hello, I want to design a variable voltage supply till 48 V@(0.1-1)A output with Input: 12 V/5V@(3A) input without a transformer. I have selected LM2586 but i am not sure of this IC still. As please can anyone suggest how can i proceed?
Thank you

 

hi kunal,
You state Vout=48V at a Imax of 1Amp that's 48Watts
Your driving source 12V or 5V at 3Amps, that's only 36Watt or 15Watt respectively.
Assuming 100% conversion efficiency.

Have you checked the datasheet.?

Do you have a draft circuit drawing you could post.?
E

 

Hello, I want to design a variable voltage supply till 48 V@(0.1-1)A output with Input: 12 V/5V@(3A) input without a transformer. I have selected LM2586 but i am not sure of this IC still. As please can anyone suggest how can i proceed?
Thank you

Your requirements and specifications are a bit vague. A variable voltage from 0-48 Volts will be a heavy lift. Your power balance is also a bit off. When you have a boost converter going from +12 V to +48 V and your input power is 12V x 3A = 36 watts. It is impossible to have an output of +48 V @ 1A = 48 watts. That would be a free energy device that produces more power out than there is power in.

1st step: Get your head out of the dark place that it is in and actually learn something about what you are trying to construct.
2nd step: Get your requirements and your power balance correct before you start picking parts.
3rd step: Do not ignore the selection of magnetic components. The success or failure of this enterprise may well depend on the selection of appropriate inductors or transformers.

EDIT: I just looked at the datasheet. You have chosen a chip designed for a Flyback Regulator. You cannot build a Flyback Regulator without a transformer. I suppose you could be an iconoclast and say none of that matters, and I'm going to go my own way. If that is the case, you don't need anything from us

 

Hello, Thank you for your response. i do not have a circuit. I just checked with LM2586 datasheet and there's 24-48 V conversion circuit on page 30, figure 53, and i changes the R1 and R2 values in the output with R1 = 10K followed with R2 = 10K in series with 24K as shown in the figure attached.

 

Hello, Thank you for your response. i do not have a circuit. I just checked with LM2586 datasheet and there's 24-48 V conversion circuit on page 30, figure 53, and i changes the R1 and R2 values in the output with R1 = 10K followed with R2 = 10K in series with 24K as shown in the figure attached.

Hello. You need to pay attention to something very basic: what you are asking for is physially impossible.

You can’t get out more power then you put in, and your input power is less than what you want out.

You need to understand W=VA which will let you test, right away, if what you want to do it possible, in this case it is not.

 

Your requirements and specifications are a bit vague. A variable voltage from 0-48 Volts will be a heavy lift. Your power balance is also a bit off. When you have a boost converter going from +12 V to +48 V and your input power is 12V x 3A = 36 watts. It is impossible to have an output of +48 V @ 1A = 48 watts. That would be a free energy device that produces more power out than there is power in.

1st step: Get your head out of the dark place that it is in and actually learn something about what you are trying to construct.
2nd step: Get your requirements and your power balance correct before you start picking parts.
3rd step: Do not ignore the selection of magnetic components. The success or failure of this enterprise may well depend on the selection of appropriate inductors or transformers.

EDIT: I just looked at the datasheet. You have chosen a chip designed for a Flyback Regulator. You cannot build a Flyback Regulator without a transformer. I suppose you could be an iconoclast and say none of that matters, and I'm going to go my own way. If that is the case, you don't need anything from us

Hello,
i understand your point but the current in the output shouldn't necessarily be till 1 A. because i know that input power itself is less than output and also i am learning and I have just started this small project so that i can do experiment on my own. And i need help as i am learning.

 

Hello, Thank you for your response. i do not have a circuit. I just checked with LM2586 datasheet and there's 24-48 V conversion circuit on page 30, figure 53, and i changes the R1 and R2 values in the output with R1 = 10K followed with R2 = 10K in series with 24K as shown in the figure attached.

That is the trivial part of the design. what does the rest of it look like?
In terms of a power balance, I see something like the following:
Input Power = 36 watts = 12V x 3A
Target efficiency 80% (because this is apparently your 1st design)
36 watts x 80% = 28.8 watts of Output Power
At +48 V, 28.8 watts means you have an output current of 600 mA. Which is a bit short of your goal. Maybe that is OK, but maybe not.

 

Hello. You need to pay attention to something very basic: what you are asking for is physially impossible.

You can’t get out more power then you put in, and your input power is less than what you want out.

You need to understand W=VA which will let you test, right away, if what you want to do it possible, in this case it is not.

Hello, thank you for your reply, you are right about it. Because with 12 V it is not possible, but with 24V it goes P=72W. So yes it's my mistake with input Voltage. So better i try with more than 24 V as an Input.
Thank you
With 24 V there will be possibilities right Sir?

 

hi,
That datasheet figure requires 18V through 36V to drive the IC, how will changing the feedback components correct for using a 12V input at 3A.

E

 

Hello,
i understand your point but the current in the output shouldn't necessarily be till 1 A. because i know that input power itself is less than output and also i am learning and I have just started this small project so that i can do experiment on my own. And i need help as i am learning.

And the first lesson you need to learn is not to put the cart before the horse. There is absolutely NO POINT in picking parts until you have your requirements nailed down.

 

That is the trivial part of the design. what does the rest of it look like?
In terms of a power balance, I see something like the following:
Input Power = 36 watts = 12V x 3A
Target efficiency 80% (because this is apparently your 1st design)
36 watts x 80% = 28.8 watts of Output Power
At +48 V, 28.8 watts means you have an output current of 600 mA. Which is a bit short of your goal. Maybe that is OK, but maybe not.

Thank you once again. The calculations are true. I am still not sure whether i should use input voltage of 12 v or change it to 24 V. Because with 24 V -->P= 72W, with 80% efficiency
72W x 80% = 57.6W (OUTPUT).
But still not sure whether to use 12 V or 24 V Input!

 

And the first lesson you need to learn is not to put the cart before the horse. There is absolutely NO POINT in picking parts until you have your requirements nailed down.

Thats true. thanks for the lesson. So now with 24V are there any other way without using a transformer?

 

Thats true. thanks for the lesson. So now with 24V are there any other way without using a transformer?

Why are we talking about transformers, when we don't even have a circuit? You already know the answer to that question because it is there in the datasheet. You can make a boost converter, but it has some limitations. What do you know about the operation of a boost converter? Do you know how to pick the inductor, and what stresses it will have to endure? How about the capacitors, and the diode; do you know how to pick them? Are you perhaps in over your head?

One more thing. Were you going to make a printed circuit board or was this going to be a one-off prototype?

You might want to take a step back and investigate these matters, by using a simulator to answer these what if questions with maximal safety and minimal expense.

 

Hi k,
Also, what is the intended use of the 48V @ 1Amp, power supply.?
E

 

hi,
That datasheet figure requires 18V through 36V to drive the IC, how will changing the feedback components correct for using a 12V input at 3A.

E
View attachment 261456

Hello, Thank you for your response. i do not have a circuit. I just checked with LM2586 datasheet and there's 24-48 V conversion circuit on page 30, figure 53, and i changes the R1 and R2 values in the output with R1 = 10K followed with R2 = 10K in series with 24K as shown in the figure attached.