DAC output to non-inverting opamp with no DC offset

[danjel]

DAC: TI DAC7562

OPAMP: TL032 or ???

I am using non-inverting opamp configuration to amplify the the DAC output to a 0-10V range. I use the trimmer and a callibration routine to make sure I can hit the 0.000V 1.000V 2.000V etc.

The trimmer is there to adjust the gain but I am trying to avoid adding an extra trimmer for nulling out the DC offset due to space limitations on my PCB.

Will I be ok using the TL032 (low DC offset) or is there some other trick to employ?

 

[KeepItSimpleStupid]

Single ended outputs generally are a real pain to deal with. Can you use a suitable IA? We hav no idea of the real requirements. But with an IA, the output reference (The "other" analog ground) and the input reference (What you "think" your reference is" can be different.

 

[danjel]

Single ended outputs generally are a real pain to deal with. Can you use a suitable IA? We hav no idea of the real requirements. But with an IA, the output reference (The "other" analog ground) and the input reference (What you "think" your reference is" can be different.

No space to add extra opamps to re-invert since single IA stage would give me a negative DC output.

Analog supply is +/-12V

The DAC is using it's internal refference generator (4.096V)

 

[KeepItSimpleStupid]

No, just switch the input leads. Check out the AD8421: https://www.analog.com/en/specialty...1/products/product.html#product-documentation

 

[danjel]

No, just switch the input leads.

Not sure I understand. Can you elaborate/illustrate?

 

[KeepItSimpleStupid]

An IA is not a standard OP amp. It's basically a difference amplifier where the gain is set by a SINGLE resistor. So, if you want a gain of -1, set the gain to 1 and reverse In- and In+. The IA amplifies the difference of (IN+-IN-) and outputs it, in this case relative to a REF. So, you get differential inputs and differential outputs.
In most cases REF has to be a low Z source.

if you have ground differences and your connecting to ground, there is no big deal.

When I did data aqusition, I often used current outputs which can be referenced to anything and differential or pseuodo-differential inputs.
One instrument I worked with, actually provided the strap for ref and ground which was very nice.

One "home made"system didn't work so well, because I failed to realize that you had like 6 instruments powered from one supply. The potentiometers were referenced to the instrument itself, but the analog reference was quite different. An AMP01 or AMP02 would have worked for each channel.

 

[ChrisP58]

If you have room for two fixed resistors, and you're not using the 2nd dac output for anything, you can do zero volt nulling in software.

The two resistors both tie to op-amp pin 6. One to -12V, and the 2nd resistor to the 2nd dac output. The resistor values will be much larger than that of R23. Choose them such that as the DAC output runs from 0V to 5V, the DC value at op-amp pin 6 runs from -10mV to +10mV, or whatever range you need.

You want to do the 0V nulling first, as it will affect the gain slightly.