Regulated vs Unregulated regrading to SMPS

  • Thread starter rama1001
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  • #1
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Main Question or Discussion Point

Hi,
Can any one explaine me what is the basic difference between the mentioned question and how it differs on the parameters like output voltage, output current, burst duty, frequency, duty cycle, burst frequency, Timing/phase shift and timing/ dead time.

I don't have any idea about the difference and also what are the paremeters we will take into consideration on both occations.
Thank you.
 

Answers and Replies

  • #2
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SMPS power supplies are all regulated.

Fish
 
  • #3
132
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can you explaine me the differences between those two. I am very beginer to this....
 
  • #4
berkeman
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Hi,
Can any one explaine me what is the basic difference between the mentioned question and how it differs on the parameters like output voltage, output current, burst duty, frequency, duty cycle, burst frequency, Timing/phase shift and timing/ dead time.

I don't have any idea about the difference and also what are the paremeters we will take into consideration on both occations.
Thank you.
can you explaine me the differences between those two. I am very beginer to this....
As Fish already said, most switch mode power supplies are regulated. After all, they have some output voltage that they are specified to deliver, right?

There are a very few applications where an unregulated output can be tolerated. One would be where you are following a DC-DC converter stage with a linear regulator stage, to supply a quiet rail to the application circuitry. Another example would be the Maxim RS-232 level shifter ICs, that use switched capacitor DC-DC circuits to make the +/-12V rails for RS-232 comm out of a 5Vdc supply.
 
  • #5
Averagesupernova
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SMPS power supplies are all regulated.

Fish
Not necessarily true.
 
  • #6
berkeman
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Not necessarily true.
Hey, ASN, can you help me with other examples of non-regulated DC-DC applications?
 
  • #7
Averagesupernova
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I know some car audio amplifiers use an unregulated supply. They will run class AB. If you think about it, we could run a linear post regulator which then feeds the collectors of the output stage of the amplifier. We will dissipate a certain amount of power in the pass transistor of the linear post regulator. If we were to eliminate the pass transistor and feed the output of the switcher (ripple free due to good filtering) right into the collectors of the output transistors now the power that was dissipated in the pass transistor is now dissipated in the output transistor. Sure, the voltage may sag on the collector of the output transistor when current demand is high compared to low but as long as the voltage does not get low enough to clip the output signal it doesn't matter.
 
  • #8
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A switched capacitor supply is a good counter example to "All".

Fish
 
Last edited:
  • #9
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thanks for your information and still, i am not able to understand the differnce between those two regarding the parameters what i have given in the first scrap. I am doing a GUI, in that i encounterd these problems. In my application, I am gonna create a checkbox(regulated) with some parameters under it. if the user press the checkbox(means regulated) and it has to display only ouput voltage, current textboxes. othe case that if unchecked(un-regulated) then it has to display burst duty, frequency, duty cycle, burst frequency, Timing/phase shift and timing/ dead time textboxes.

Now, can any one explaine me in unregulated case about that parameters and internal meaning of all the parameters.
 
  • #10
berkeman
Mentor
57,268
7,251
thanks for your information and still, i am not able to understand the differnce between those two regarding the parameters what i have given in the first scrap. I am doing a GUI, in that i encounterd these problems. In my application, I am gonna create a checkbox(regulated) with some parameters under it. if the user press the checkbox(means regulated) and it has to display only ouput voltage, current textboxes. othe case that if unchecked(un-regulated) then it has to display burst duty, frequency, duty cycle, burst frequency, Timing/phase shift and timing/ dead time textboxes.

Now, can any one explaine me in unregulated case about that parameters and internal meaning of all the parameters.
Regulating the output of a switching power supply involves feeding back a measurement of the output voltage, and adjusting the duty cycle of the switching circuit to achieve the output voltage regulation. If the output voltage is to be unregulated, then it sounds like your program lets you set the switching duty cycle (and those other parameters) by hand to some steady-state value.
 

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