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14.8V to 12V,5V and 3.3V voltage regulator

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valchid

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Hi guys, I want to make a power supply which provides 3 regulated voltage lines: 12V,5V and 3.3V from a 14.8V battery.Whats the best way to do this without dissipating too much energy.Thanks
 

valchid said:
. . . a power supply which provides 3 regulated voltage lines: 12V,5V and 3.3V from a 14.8V battery.Whats the best way to do this . . . .
Click to expand...
The answer to this will also depend on how many Amps you wish to provide at each of these 3 voltages.

Could you please specify the maximum current on each voltage output?

That should help us to give you a useful answer.
 
For better efficiency, pls use DC/DC for 5V and 3.3V, and use LDO for 12V
 
To reduce cost & components, Use LDO for 12V, DC/DC for 5V & again LDO for 3.3V but I/p of LDO connected to 5V o/p instead of directly to the battery. with battery application, I dont think current requirement is more than 1A.
 

Hi,
Use an LDO regulator to get 12v output, such as this one here: Product Folder - KA278R12C - 2A Fixed 12V Low Dropout Voltage Regulator (LDO), Fairchild Semiconductor - Global Leader in Power Optimization
To obtain 5v, use a switching regulator, such as L4971 (DIP package): http://www.datasheetcatalog.org/datasheet/stmicroelectronics/5598.pdf
To obtain 3.3v, use another LDO regulator to obtain 3.3v from the 5v output, such as LM1117v33: http://www.datasheetcatalog.org/datasheet/stmicroelectronics/2572.pdf

Hope this helps.
Tahmid.
 
ykcor said:
you can also use lm317
Click to expand...

Hi,
LM317 can be used, but valchid has said:
Whats the best way to do this without dissipating too much energy.
Click to expand...
LM317 would waste a lot of power, the situation becoming worse as the input voltage and output current increase.

Hope this helps.
Tahmid.
 

thanks for the responses guys, as mentioned earlier i think the best idea would be to use a LDO for the 12V and switching regulators for the 3.3 and 5V
 

be aware that you will not always get 14v from your battery. a car battery still works at 11v
but your ldo at 12v output will not work if you only have 11v at input
a step-up-down controller will...
regards.
 
Kripton2035 said:
be aware that you will not always get 14v from your battery. a car battery still works at 11v
but your ldo at 12v output will not work if you only have 11v at input
a step-up-down controller will...
regards.
Click to expand...

I see. Is there some sort of step-up controller which i can use to step u the voltage once it drops to below lets 13V to keep the 12V LDO regulator working?
 

Last edited:
Hi,

Just use a buck-boost regulator as posted by Kripton. This circuit will try to keep the output voltage consistent. When input voltage drops to below the output voltage, it steps it up (boost) and when the output volt rises above the output voltage, it steps it down (buck). With the right type of circuit, you can use just the regulator and you won't even need that LDO.

Hope this helps.
Tahmid.
 
If the load current is not too big(<=0.5A), charge-pump can be used for voltage step-up. It will be cheaper.
 

Many times I used National simple switchers IC. You need just a few external components...

Look:
**broken link removed**

Here you can find everything you need (there you have application (WEBENCH® Designer) that calculate all components and give you schematics).


Mr.Cube
 
how can I use WEBENCH with custom components?

I am using LM3150 switcher controller and I want 1 to 15V variable output

is that possible with this IC?
 

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