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[SOLVED] Best voltage Regulator IC

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baby_2

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Hi,
I want to have a powerful and very safe voltage regulator.Input voltage is 24 volt and it can be up to 35volt and in my circuit I need 5 and 3.3 voltages.
First of all I choose Lm2576 for generate 9 volt(or any other voltage that you assume it is good for my purpose) dc and I want to use decrease it to 5(1A) and 3.3(1A) volt. So it is good to use another switching lm2576 for decrease to 5 or 3.3 or it's better to use a linear regulator? (Safety is more important than number of components)
and which regulators are good for my purpose with high reliability?

In addition , I don't want to design a power supply that I should use SMPS circuits or storage transformers and other like these So I will appreciate to help me to select good components for my purpose.

Thanks
 

I f wee assume that your system consumes full power ( 1A at each output ) and under the max. permissible input voltage so 35V.
The power dissipation will be 35-5=30V*1A=30W and 35-3.3=31.7*1A=31.7W so final dissipation will be around 62W.
If you use Linear Regulators with an external Pass Element, you can realize this system supply.
 

Thanks for your replay.
Actually in the first stage I want to use switching IC to convert 35volt to 8 volt. In this case dropped-voltage I think is less (30 and 31.7) for the first step ( Am I right?) because it's internal switch gets off when it drives load well. and my problem is that it's better to use another switching IC to convert 8 to 5 and 3.3 or it's better to use two regulated IC? safety, low power dissipation are more important. In addition for the second stage which IC should I use and recommend?
 

That will work but be inefficient. The combined currents of the 5V and 3.3V loads will have to pass through the first regulator. Given their very low cost, it would be better to use two switching regulators, one with 5V output and one with 3.3V output but join their inputs together to the 24-35V source.

Brian.
 
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    baby_2

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All of this also depends on application. I tend to used a switching regulator followed by a linear regulator for very clean, very low noise applications and a switcher (as Bigboss or betwixt suggest) when very low noise supply is not critical. I do not know that one design architecture would be more safe than the other.
 
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All of this also depends on application. I tend to used a switching regulator followed by a linear regulator for very clean, very low noise applications and a switcher (as Bigboss or betwixt suggest) when very low noise supply is not critical. I do not know that one design architecture would be more safe than the other.
Absolutely agree..
First stage will be a Switch Mode regulator in order to reduce 35V down to a reasonable value and then 2 Linear Regulators.
That's it..
 
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Thanks for your explanation and contributions
Yes, the 5v and 3.3v output should power up the micro-controller and other logical IC that they are so too sensitive to their input voltage.
Given their very low cost, it would be better to use two switching regulators, one with 5V output and one with 3.3V output but join their inputs together to the 24-35V source.
in this statues if one regulator fails it's output can be more than 5 and 3.3 volt and it can burn my other devices?
All of this also depends on application. I tend to used a switching regulator followed by a linear regulator for very clean, very low noise applications and a switcher (as Bigboss or betwixt suggest) when very low noise supply is not critical. I do not know that one design architecture would be more safe than the other.
if I use switching regulator and two linear regulator what linear regulator do you suggest that can withstand up to 12 volt (input(for Safety)) and output current 1A?(I can't see any low-drop linear regulator that can power up more than 800mA)
 

Hi,

For 1A one option could be a MIC29300-3.3WT and a MIC29300-5.0, 3A LDOs, this is the name of the datasheet if you want to look into it: MIC29150/29300/29500/29750 High-Current Low-Dropout Regulators, as Micrel is now a part of Microchip Google results brings it up as ww1.microchip.com/downloads/en/DeviceDoc/mic29150.pdf
 
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Thanks for your explanation and contributions
Yes, the 5v and 3.3v output should power up the micro-controller and other logical IC that they are so too sensitive to their input voltage.

in this statues if one regulator fails it's output can be more than 5 and 3.3 volt and it can burn my other devices?

if I use switching regulator and two linear regulator what linear regulator do you suggest that can withstand up to 12 volt (input(for Safety)) and output current 1A?(I can't see any low-drop linear regulator that can power up more than 800mA)

This may be your optimum choice.
https://www.ti.com/product/reg104
 
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