Invert output from DAC

[MarcoAndarcia]

Hi,

I am working on a project in which I have to invert the voltage from a DAC that I have chosen. This DAC works from an I2C bus; however it can only produce voltages from 0-5V, I would like to be able to invert this output and make it from -5V to 0V. I know I can build an inverter buffer using Op-Amps however my end goal is to be able to produce outputs from -5V to 5V. I believe there is an IC capable of turning my positive voltage and convert it into negative voltage if I choose so. I haven't been able to find this IC unfortunately, nor I2C DAC that produce negative and positive voltages with 14 bit or higher resolution.

Thanks in Advance.

 

[betwixt]

You can do this with many op-amps. What you need to do is offset the voltage by 2.5V so it ranges from -2.5 to +2.5 then amplify it x2 to make it -5.0 to +5.0.

Brian.

 

[MarcoAndarcia]

Hi Brian

I am leaving this option for last since I would have to take into account the offset of the op-amp, and I would need a low noise ref psu. I am currently looking into SPI -DAC but haven't found one with at least 4 converter and is 16 bits.

Thanks.

Marco.

 

[BradtheRad]

In case this helps with the topic now (or later)...

Here's a screenshot of an op amp converting an input of 0-5V, to an output of -5 to +5:



The second configuration inverts the signal, in case that is what you mean by the word 'invert'.

 

[kripacharya]

does your DAC produce these voltages directly, or does it output(/input) a current ?

 

[MarcoAndarcia]

Yes, I know I can make an inverting amplifier with gain 2 but it introduces some noise, and I would have to workout the offset of the op-amp, I think I will have to do it anyways, I have been looking for a part that has the op-amp and internal reference in the same IC. The DAC that I am using right now outputs voltage, but only from 0-5V.

 

[FvM]

Wouldn't it be reasonable to use the same reference as the DAC rather than using a second reference? This reduces the problem to a trivial 1 OP 4 resistors design.