[moved] Need of regulator circuit...

[Savitha Mahendran]

Hello Everyone!!!
I need help in designing a voltage regulator circuit. My requirement is the output voltage of the regulator has to be constant 6V. Input may vary from 3V to 12V. For this range of input values the output should be 6V. What should I do??? I tried of buck boost converter also. But when going for that option I have to compare the input voltage with a reference voltage of 6V. But there is only one supply source that is incoming voltage so to provide reference voltage itself I have to regulate Vin. Please anyone give me an idea to solve this problem...

Thank you..

 

[KlausST]

Hi,

But when going for that option I have to compare the input voltage with a reference voltage of 6V

I don't know what you mean.
*****
Go to a DC DC converter IC manufacturer internet site. They usually have interactive selection guides.
Fill in the form with your data and you will get a list of ICs that are able to work as desired.

Select a part, download datasheet and read it carefully. Application notes may further assist you.

Look for "buck boost" or "sepic"

Klaus

 

[Anna Conda]

A sepic converter driven from an MC33063 33064 will do the trick.... has its own regulator and works down to 3V

 

[srizbf]

you have to compare the incoming with with a reference voltage ,but not 6v as i/p may be 3v.
so use a reference diode and compare its voltage with your o/p.

 

[Savitha Mahendran]

And what I meant is when I am going for comparison I want to provide reference voltage but i have only incoming voltage as source...

Sir, but I don't want to use any ICs i want to complete it with the help of discrete components only... @Klaus

 

[KlausST]

Hi,

If you want to build it on discrete devices, than you may have a schematic in mind.
Could you please show us your circuit, so we can better understand the problem.

Klaus

 

[Savitha Mahendran]

Sir i am just designing boost converter now

 

[srizbf]

... for comparison I want to provide reference voltage but i have only incoming voltage as source...

from the incoming source only you have to generate the reference.

 

[KlausST]

Hi,

Sir i am just designing boost converter now

But as far as i understand you need buck boost functionality.
I recommend to design a combined "buck boost" or "sepic" converter.

You could read some datasheets on how the "buck boost" or "sepic" ICs work... just to get some ideas for your design.

Klaus

 

[BradtheRad]

Since a buck-boost inverts supply polarity, your output is in the negative polarity. The problem is how to compare it to a reference of -6V (or a convenient divided-down level).

You need to measure negative volt levels. You need a device which can detect negative polarity, without harm.

It must recognize whether the level is above or below -6V. However a -6V reference is unavailable since that is outside the range between 0V ground and VCC.

An optocoupler is able to do the job. It is commonly used when galvanic contact is not wanted between sections of a circuit.