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Positive to negative voltage converter

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guyz

i have a 12-12.6V dc input and i need such chip which gives me -12v dc as a output.
Initially i search lm7912 for this purpose and then i came to know that it needs also negative input(correct me if i am wrong please as i am not crystal clear about it)

so can u suggest some chips to accomplish this task.
 

Is this for a power supply or a signal conversion?
If it is a power supply what is the current requirement?

Alex
 

A 7912 is a voltage stabilizer, you feed it with 14 - 30 volts input and you get 12 V output. What you need is a voltage converter for a low current application or a DC-DC power supply for a high current application. What sort of current do you require?
Frank
 

Hello Dear miscaller
It is simple . but how much current do you need ?
IF you want convert , +12 volt to -12 volt , you'll can use buck-boost arrangement .
Best Wishes
Goldsmith
 

As mentioned, we need to know your current requirements on the negative 12V. However...

Switched capacitor convertors are nice and easy:

The ICL7660S converts a +1.5 to +12V into an equal magnitude negative output. It only needs two capacitors for a basic circuit - no inductors.

www.intersil.com/data/fn/FN3179.pdf

The LT1054 is similar and gives a bit more current:

LT1054 - Switched-Capacitor Voltage Converter with Regulator - Linear Technology

Many manufacturers offer ready-built modules to do this at higher currents if you want to spend the money.
 
i am using LM339 amplifier as a comprator.The input signal (0-5V rectangular wave) will be changed in 12V to -12V.For the Vcc i have 12V but for -Vcc i don't have -12V as i am using single power supply.So i am suppose to find a chip which converts 12 volts to -12V.The current drawn by all circuit(as its a just a part of circuit lm339 etc etc) is 20-30mA maximum.
So can u suggest any solution
 

miscaller said:
i am using LM339 amplifier as a comprator.The input signal (0-5V rectangular wave) will be changed in 12V to -12V.For the Vcc i have 12V but for -Vcc i don't have -12V as i am using single power supply.So i am suppose to find a chip which converts 12 volts to -12V.The current drawn by all circuit(as its a just a part of circuit lm339 etc etc) is 20-30mA maximum.
So can u suggest any solution
Click to expand...

Hai try this device

www.ti.com/lit/ds/symlink/ptn04050a.pdf

I have used this in a project to convert from +5 to -5 V. It is capable to convert the voltage upto -15V
 

This might sound funny- Why don't you change the terminals? Give the positive terminal to the ground then the other one becomes -12V
 

iVenky said:
This might sound funny- Why don't you change the terminals? Give the positive terminal to the ground then the other one becomes -12V
Click to expand...



Just try it jVenky
From a single battery,take 4 terminals out.Two positive and two negative then for 12V ground negative terminal and for -12 V ground positive then u will suddenly realize that u have shorted your battery.

Secondly if it is so simple then why many companies are providing different chips which are mentioned above

---------- Post added at 10:39 ---------- Previous post was at 10:38 ----------

Thanks karthikkrv85.
I read its datasheet but it is not available here.
 

miscaller said:
[/COLOR]Thanks karthikkrv85.
I read its datasheet but it is not available here.
Click to expand...

Hai... As a module if you dont get that device, then try this chip.

cds.linear.com/docs/Datasheet/3580fg.pdf

In this, they have given a typical circuit to convert from +5 to -5 V.

This may be helpful i think.

All the best
 

Thank you so much guyz

my problem is sloved now

i am using ICL7662 it gives me -11.7V pprox with the input of 12V.
and ICL7660 can also be used for the same purpose

:wink::smile:
 

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