Negative output Voltage

Thank you Jhun,

But my goal is to find a to find a circuit with a negative voltage at the output (-5V). Do you how  I guess I have to calculate the component values ​​to get the -5V. I found this electronic assembly but it is enough that I adapt a little to find the -5V right ?

Thank you for your helps

Regards

That is a negative output.

In the schematic,

The referenced ground is the VNEG output.

The circuit I sent is an alternative as to how to generate a negative output from a buck controller in the simulation.

Unknown said:

The referenced ground is the VNEG output.

Sorry but I can't see the VNEG output in your schematic. Where it's (sorry I'm a beginner under LTspice).

Where must I take my probe to see the negative voltage ?  

In this particular connection, ground acts as the VNEG terminal of the output and the OUT acts as the positive terminal of the output.

If you want to see a negative voltage, search on the LTSpice documentation how to measure a voltage with a certain reference.

Refer to this documentation: AN-1083 (Rev. A) (analog.com)

Now I can see the negative voltage

I looked nowhere I just guessed your explanation only. But my question is Can I take my ground as the negative value ? In my application I need to supply my AOP with a voltage symmetry with a common ground. So if I connect this point to my ground 

Where is my common mass to supply my AOP with +5V an -5V ?

If you can see the voltage supply, the supply negative terminal of the supply is the OUT pin. This is the true ground.

I just used the ground symbol as the VNEG terminal of the output because some of the buck ICs has internal ground, which might cause an error when connecting ground as the positive terminal and a floating ground as the NEGATIVE terminal.

Unknown said:

If you can see the voltage supply, the supply negative terminal of the supply is the OUT pin. This is the true ground.

So a little complicated for me, after your explanation the common ground is this point name OUT right ?

And the negative voltage is this point name 'GND' right ?

So I think I'll open a new ticket to make another electronic assembly that provides +5V which I put together with your assembly (schematic here) to see if I have +5V and -5V with a common ground. This point is very important for me to supply my AOP

Thank you for your helps

Regards

Hi,

After simulating 2 electronic diagrams +5V and -5V, I assembled the 2. And I don't get the expected result. Do you know where is my mistake ? 

In my +5V circuit it works

But in my -5V something is wrong but it works independently very well

I don't have -5V, I don't get the expected -5V but +12V.

Thank you for your helps

Regards

PJ : The file of simulation

Yann DOEzone-LTC1624_+5V_-5V.zip

Your GND pin should still be grounded, not -5V.

When you connect your input between VIN and VOUT of a buck regulator, it will become an inverting buck boost regulator with GND being the VNEG AND REFERENCE of the controller.