# Inverting Dc

#### Airskout

##### New Member
Hello all , I am working on a project and i've come to a roadblock. I am( just finishing university so please don't hate me ) looking for a component that can "invert" +5V to -5V . The numbers are examples but i am working with similar voltages. I haven't tried logical gates yet but might resort to . Any ideas welcome . The project is in smt so not huge components.

#### rjenkinsgb

##### Well-Known Member
Look at the MAX660 or ICL7660

Those are 8 pin ICs that work as capacitor charge pumps, and are designed to create low current negative supplies.

For a basic +5 to -5 converter you just need the IC and a couple of capacitors.
Data here:

#### dr pepper

##### Well-Known Member
If you want to be really basic you could even use a 555 charge pump circuit.

#### Diver300

##### Well-Known Member
Are you wanting to transfer power like this?

Alternatively is it just a signal? That would be where you have for example as signal that might be 1 to 5 V and you want to make 1 volt in give -1 V out, and 5 V in give -5 V out, and you already have any supply voltage that you want.

#### Airskout

##### New Member
If you want to be really basic you could even use a 555 charge pump circuit.
This looks promising ill check it

#### Airskout

##### New Member
So small miscalculation i need it to run up to 12V cause of some displays i need to power
Ultimately i would like it to return the whole input voltage negative and to help with the answers atm i am using an LM317L capping the voltage to 10-12 V using a potentiometer with a variable input from 12-24 V and i want to be able to invert the output of the microchip to power other components

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#### Airskout

##### New Member
Are you wanting to transfer power like this?

Alternatively is it just a signal? That would be where you have for example as signal that might be 1 to 5 V and you want to make 1 volt in give -1 V out, and 5 V in give -5 V out, and you already have any supply voltage that you want.
Ultimately i would like it to return the whole input voltage negative and to help with the answers atm i am using an LM317L capping the voltage to 10-12 V using a potentiometer with a variable input from 12-24 V and i want to be able to invert the output of the microchip to power other components

##### Well-Known Member
Will simply using a full wave bridge work?
I have used it for 'steering' bi-polar DC to a uni-polar source as well as AC as a universal interface.
Max.

#### crutschow

##### Well-Known Member
If you need any significant power, then you could use a switching regulator to get a negative voltage from a positive.
How much power do you need?

#### atferrari

##### Well-Known Member
Is it a signal or is it power?

##### Well-Known Member
i want to be able to invert the output of the microchip to power other components
Invert is not always the same as reversing polarity!
Max.

#### Airskout

##### New Member
Invert is not always the same as reversing polarity!
Max.
Ok my bad on that one reversing polarity is what i meant

#### Airskout

##### New Member
Is it a signal or is it power?
It's power maximum current about 100mA

##### Well-Known Member
So the bridge will do that.
What are the circuit details?
Max.

#### rjenkinsgb

##### Well-Known Member
A TC962 may do the job - it's a cross between a max660 and icl7662, up to 18V input and 80mA out?

That's the nearest I can find so far in a simple device..

#### Nigel Goodwin

##### Super Moderator
I would suggest you post EXACTLY what you're trying to do, and why, and post some schematics - I don't have the faintest clue what you're after, and every one is just making wild guesses.

#### dr pepper

##### Well-Known Member
Some info:
100ma is on the high end current wise.
From what you said I'd be putting a simple smps together, however thats a reasonably demanding task.
This circuit generates a negative o/p:
Again not reccomended unless you have some experience.

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#### shortbus=

##### Well-Known Member
A TC962 may do the job - it's a cross between a max660 and icl7662, up to 18V input and 80mA out?

That's the nearest I can find so far in a simple device..
Hi, would that chip work to keep a high side mosfet on continuous? Looks simpler than the normal charge pump to do that.

#### rjenkinsgb

##### Well-Known Member
would that chip work to keep a high side mosfet on continuous?
To keep a high side N-Channel FET on?

If the voltages are appropriate and you configure it in voltage doubler mode, it should be suitable - you could generate eg. 15V above the main circuit positive supply.

If the supply is higher than 18V, possibly put a 15V zener across the IC with positive direct and a resistor for the negative input?

#### Airskout

##### New Member
I would suggest you post EXACTLY what you're trying to do, and why, and post some schematics - I don't have the faintest clue what you're after, and every one is just making wild guesses.
Alright tomorrow i will post more info of the project so you can help me more i guess but you are already helping guys