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pulsed power supply current delivery

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Zak28

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If a power supply is rated to 8amps max output can it power a switching load which peaks to 11-14 amps?

The load average and RMS current being 3-5amps. Wouldn't this damage the power supplies internal filter capacitors?
 

This is like saying my car has a top speed of 150 KPH, will it be damaged if I do 250KPH?

There is no guarantee the power supply can manage 8.1 Amps so asking if it can manage 14 Amps is a nonsense question. What it can sustain and its peak output depends entirely on the design of the PSU and cannot be determined by calculation or guesswork.

Brian.
 

Well what frequency is your load switching? If we're talking Khz I tend to think the output caps will take it.

Also you could add your own external capacitor or post LC filter if you're really worried.
 

If the power supply is rated at 8 A, a good design will work, OUTSIDE of rating to about 10 A.
BUT using it outside rating will likely void any warranty.
If I designed it, it would automatically current limit at about 8.5 to 9A, so you could never get 11 to 14A.

As for damaging the capacitors, maybe.
If it didn't protect itself from abuse, it would likely burn up fairly quickly.
 

Hi,

If the power supply is rated at 8 A, a good design will work, OUTSIDE of rating to about 10 A.
Click to expand...
Why? For sure it MAY work, but there is no guarantee.
If it fails, the only one to blame is the one who does not keep on specifications.

But for sure an external filter will can supply pulses of 14A while drawing less than 8A from the power supply.
It depends on the duty cycle of the pulses ... and a bit on filter and pulse frequency..

Klaus
 

To be clear, given that most power supplies have C on the very output their current limiting and shutdown circuits can't see high frequency ripple if they even wanted to.
 

For an intelligent question, I would expect to hear some details about the power supply and a rough specification of current waveform.
 

There is no amount of information that you are going to give here that is going to be conclusive. However, the more the info, the higher the probability that the answer you're going to get would be correct.

There are a lot of things that would affect how the power supply behaves in this scenario. This ranges from saturation of the feedback loop to saturation of the magnetics to saturation of the duty cycle if it had a programmed maximum duty cycle, and so on.


However, I think the best way to go about it is for you to give more info like FvM has asked for, but at the end you'll still need to risk it on trial.

Sorry, that's always something to face when doing donts and the consequence could be very high.
 

Below is a buck converter which peaks at 8.21 A internally.
The power source sends smooth continual 2.27 A. It does not need to provide 8.21 A.
The key is to use a type of input filter made from a series LC. The capacitor delivers a large pulse of current to the converter during the duty cycle, then is replenished during Off-time. The current draw from the power source is an average amount.

buck conv clk-driven 30V 2A to 12V 5A LC input filter smooths.png
 

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