Turning a positive vref into a negative reference?

[blueroomelectronics]

I have a 4.096V reference for a ADC and I'd like a -4.096V reference for the -VREF on the ADC.
Question would an OpAmp do the trick or do you have a better suggestion / idea?

 

[crutschow]

An op amp connected as a unity gain inverter will work well. Depending on the accuracy you require, you may need a low offset, low noise op amp, and precision resistors (perhaps 0.1% tolerance, or 1% resistors with a trimpot) to accurately generate the voltage level.

There are other methods, such as a flying capacitor switch, to invert the voltage, but that is more complex and has its own accuracy and noise concerns.

 

[Hero999]

I don't see why you need a negative reference, you can easily bias an ADC input so it can measure negative voltages.

 

[Pommie]

Can the Vref be wired like a zener?
I.E.
Vref Vdd to +supply,
Vref Output to ADC Gnd,
Vref Gnd to ADC -Vref plus a resistor to -supply

Mike.

 

[Speakerguy]

Opamp will introduce inaccuracies unless you get something with nice DC specs. If it is a shunt reference I would to what Pommie suggests and just use two.

 

[Boncuk]

Hi Bill,

in order to invert an OpAmp for negative output you must use a negative supply voltage anyway. Use an LM7905L and trim the output to the desired value.

Regards

Hans

 

[blueroomelectronics]

It's for an CS5560 DS ADC, I can run it in single supply mode and cut the grief of the dual supply. Thanks for your suggestions.

 

[Mikebits]

Check out this part.
https://www.electro-tech-online.com/custompdfs/2009/01/MAX828-MAX829.pdf