power supply questions
power supply questions
(OP)
Hi All,
I just joined this forum.
I am planning to work on power supply design very soon. I wanted to make sure my ideas going to work or not. :)
One of our products running on both AC (85-265VAC) and DC (20-28VDC) power supply. We have those as separate supply circuit at this point.
I am planning to design common power supply circuit which can take both AC and DC power supply. Is it possible? If yes, I am looking for help on the same.
The output of power supply should be 24V and 5V in both situations.
I will come up with all other parameters like load, current requirements etc later on.
Before I move ahead I want to know is it possible to design such a circuit that can sense AC or DC and behaves according that?
Or I can explain same thing in little different way: - "How to distinguishes/sense AC(85-265) voltage and DC(20-28) voltage signal?" Once I know the method, I can use it before Transformer stage and after that transformer behaves according to incoming voltage that will sync up with secondary side of transformer.
Thank you for looking in it!!!!!!
pshah72
I just joined this forum.
I am planning to work on power supply design very soon. I wanted to make sure my ideas going to work or not. :)
One of our products running on both AC (85-265VAC) and DC (20-28VDC) power supply. We have those as separate supply circuit at this point.
I am planning to design common power supply circuit which can take both AC and DC power supply. Is it possible? If yes, I am looking for help on the same.
The output of power supply should be 24V and 5V in both situations.
I will come up with all other parameters like load, current requirements etc later on.
Before I move ahead I want to know is it possible to design such a circuit that can sense AC or DC and behaves according that?
Or I can explain same thing in little different way: - "How to distinguishes/sense AC(85-265) voltage and DC(20-28) voltage signal?" Once I know the method, I can use it before Transformer stage and after that transformer behaves according to incoming voltage that will sync up with secondary side of transformer.
Thank you for looking in it!!!!!!
pshah72
RE: power supply questions
> DC input components capable of handling AC, which means bigger components and more of them
> AC sensing that switches to DC if no AC present; still need something that can convert both AC and DC, but possibly at lower power
If the customer's intent is to eventually use only one input or the other, then the supply as described incurs a weight, power, and reliability penalty for carrying all those extra components that aren't actually going to be used.
TTFN

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RE: power supply questions
For the AC source, you also have to think about the myriad of standards and approvals that would be required. Many power supply bricks are simply covered with logos of all the approval agencies.
That being said, it would seem that a universal bulk power input (rectifier, filter) followed by a *very wide range* (20 to 375 volts) DC-DC converter stage is *basically* all that would be required (ignoring all the rules and regulations for the moment).
Detecting and switching is probably fraught with unexpected failure modes and dangers.
RE: power supply questions
One thing you have not indicated is the power level involved. If this is a real product and not a one-off, then with the AC input you're going to need UL or CE approvals for most countries. These regulatory requirements may be in conflict with your additional DC input requirement.
RE: power supply questions
RE: power supply questions
Then you only need to spent the other 90% of the design dealing with edge-case scenarios caused by power supply fluctuations!
RE: power supply questions