Creating voltage supply of 5v, 10v and 20v

[Raintree]

bridge rectifier 5v 10v voltage supply

Hi all,

If i want to make 3 voltage supply of 5v, 10v and 20v, how should i connect? Is it possible to have a supply of 5V and from there, i amplifie to have 10v,20v?
If using this, the supply voltage for the opamps need to be above 10V. what should i do to have all supply voltage at 5V and outputs 10V and 20V?

Thanks,

Raintree

 

[IanP]

Re: creating voltage supply

You can build 5V power supply and then step the voltage up to 10, 20 , etc.
Depending on current requirements there are several options:

Low currents (20-100mA) dc-dc charge-pump converters

Medium currents (100mA-2A) boost switching regulators

For both try MAXIM-IC, National Semicoductors, ...
They support samples programs and have a lot of application notes.

 

[platonas]

Re: creating voltage supply

I dont understant why u need to step-up the 5V supply.
You may use a 24V ac transformer and connect 3 different regulators to get the 3 different voltaged, one for the 20v, one for the 10v and one for the 5v. This solution is cheaper.
Step-up is recommended if you have only 5v available. If this is the case then you need step-up regulators in order to have good efficiency. (Is it for a battery powered equipment?)

 

[Raintree]

Re: creating voltage supply

hi all,

i need 3 different voltage supply to 3 different circuit on the same board so how should i do? If using the op amps how should i connect?

The 3 voltages are 5V, 10V and 20V

Thanks,
Raintree

 

[kukitron]

Re: creating voltage supply

This is a basic tumb of rule for a power supply designer,

You need to keep in mind a desing for the highest voltage that you need, from there, you can just get a few voltage regulators,

An opam is not the best solution, even if you are intending to use those voltages as a reference for a digital circuit,

In that way you can warranty a high performance for all voltage lines,

Cheers

 

[usernam]

Re: creating voltage supply

Since you need voltage supply for a circuit on your board you can always take power from the mains and use a transformer to transform it to a lower voltage.
Then after full wave rectifying the transformed voltage you can just use a voltage regulator to get the reqd DC voltages. Or if you don't mind the power loss you can use a voltage divider.

 

[electron_boy]

Re: creating voltage supply

u can just connect 0-24v transformer and tap the voltages at 5,10 and 20 v respectively. and this is simpler

 

[dkace]

Re: creating voltage supply

Well, why up and not down? What is your initial power supply? Is it AC or DC? You have +5V and you are searching to step up? I think the solution with the linear converters is better if you have a power supply of say 24V and take 20, 10 and 5 in the output of the converters. If you have an AC voltage you'll just need a bridge rectifier and that's all.
Check the books forum. I downloaded several books for DC-DC converters from there. I think it will most helpfull.
D.

 

[big porkus]

Re: creating voltage supply

The two basic methods are:
-Linear regulator
-Switching regulator

The best way to do this depend deeply from the MAX current
that you need.

If the current is not so high < 1A, and they have all the same GND
the linear method can be the simplest,
and i agree with the cascade solution purposed by "electron_boy".
In this case you can use the 3 pin regulators as :
7805 , LM317 , etc.....

Another site that you can try is:
h**p://www.linear.com/

enjoy
;-)