6-V to 5.2V linear regulator

[petelms]

Hello!

I would like to know how it is possible to make a linear regulator from 6-V to 5.2V. I have already made a little board like this (mine is with 6-V to 5-V regulator) on Youtube:

But the problem I'm having is that my device needs 5.2V and 5.0V is not enough. I want to make a linear voltage regulator, not any switching one.

Thank you!
, Pete.

 

[kellys_eye]

There are devices called 'low drop out' regulators and even 'ultra low drop out' that will operate from as low as 50mV above the required output voltage i.e. 5.2V output requires only a 5.25V input!

https://www.mouser.co.uk/ProductDetail/STMicroelectronics/LDCL015M33R?qs=GkDVaEP5dcsPPwVMZtuXlw==

but a lot depends on the current you want it at?

 

[bertus]

Hello,

A voltage difference of only 0.8 Volts will be quite a challenge.
The 7805 shown in the video already needs about 2 Volts difference.
The BA00CC0 needs only 0.5 Volts difference.

Bertus

 

[petelms]

Thanks for the answers! My load current will be at least 1.5 amps. 3 amps would be the best.

 

[Bluejets]

My load current will be at least 1.5 amps. 3 amps would be the best.

You might be pushing it uphill for that requirement.

 

[bertus]

Hello,

The BA00DD0 will be able to handle 2 A.
You will not find a regulator for 3A.

Bertus

 

[CircutScoper]

Hello!

I would like to know how it is possible to make a linear regulator from 6-V to 5.2V. ...

But the problem I'm having is that my device needs 5.2V and 5.0V is not enough. I want to make a linear voltage regulator, not any switching one.

Thank you!
, Pete.

Hi, Pete

Question: What's the source of your 6V input and how stable is it? For example, if it's unregulated or coming from a battery, it would be pretty fanciful to imagine that it's stable to 0.8V (13%) in the first place. Have you measured it under a 3A load or is this all theoretical?

 

[petelms]

The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.

 

[CircutScoper]

The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.

Then even if it is a LARGE battery, you will likely NOT have a true 6V for input to the regulator -- at least not for long. For example, here's a typical discharge curve for an alkaline D cell. Note the immediate drop when the load is first applied.

To see what reality holds in store for your battery, put a 4 Ohm (at least 10W) resistor across your battery and watch what happens with an accurate voltmeter.

 

[CircutScoper]

The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.

PS: Having no idea what you think a "normal 6V battery" might be, I used 1.5V alkaline D cells as an example of a fairly "large" battery. Their typical nominal amp-hour rating is ~15AH. But as you can see from the graph above, a 6V battery made from four of them connected in series would drop below 4 x 1.3V = 5.2V in just a (very) few minutes when connected to a 2A load.

So the good news is you may not need a regulator at all!

 

[Martaine2005]

Why not just put a diode in series?
Would approx 5.3V be too much?.


Martin

 

[Bluejets]

I'm wondering why the op has such a dislike for a dc dc converter.

 

[petelms]

Yes, normal battery can really mean anything. - When I said "normal battery" I actually meant huge 6V 140ah battery. And the reason why I want to use linear regulator is that I want to get rid of the EMF interference which normal switching DC-DC converters have.

 

[Bluejets]

And just what is it that demands required specs.?

 

[petelms]

Why not just put a diode in series?
Would approx 5.3V be too much?.


Martin

This sounds intresting! How do I put diodes in series? I'm beginner with these so I would need very clear instructions. - What kind of diodes? And is it 5.3V the lowest you can get from 6-V battery with diodes?

 

[bertus]

Hello,

A standard diode will drop about 0.7 Volts.
A shottky diode will drop about 0.3 Volts.

Bertus

 

[Bluejets]

Your 6v battery could be as much as 7.0v when fully charged and possibly as much as 8v while under charge conditions.
How did you intend to deal with that aspect?

 

[kellys_eye]

my device needs 5.2V and 5.0V is not enough.

....and just what 'device' is it that's so voltage critical?

We need ALL the information to make a reasoned response - if we end up saying 'you don't need anything, just use the 6V' after numerous posts we won't be thanking you for wasting our time.......

 

[CircutScoper]

Yes, normal battery can really mean anything. - When I said "normal battery" I actually meant huge 6V 140ah battery.

That's good news. Then all you have to worry about is its temperature coefficient -- about -0.01V/oC if it's lead-acid, although you didn't say..