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Scaling 0/3.3V ADC and DAC to -10/+10V?

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Texton

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Hi all.

I got this project, where i am using a microcontroller (PSoC5) which has both DAC's and ADC's build in. Theese are both 0V to 3.3V (the ADC can measure this interval and the DAC can generate it).

Now I have to do some regulation/digital filtering with the microcontroller, and for that I need to make the ADC measure -10V to 10V and the DAC generate the same.

I got some ideas: a voltage divider to scale down for the ADC and a OP AMP for scaling up the DAC output.

But I wanted you guys opinion, experience and ideas for this? is there a better/safer/less noisier way? and btw. I need a bandwidth at 50kHz.

Thanks :)
 

BradtheRad

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You are on the right track. Here's what I come up with.

10 VAC input,
0 to +3.3 VDC output,
using two resistive dividers:



0 to +3.3 VDC in
10 VAC out,
using op amp at 6x gain
(attach the lower left resistor to whatever is your negative supply)



The scope sweeps are triangle waves in order to demonstrate that the response is linear.
 

Texton

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Yes that was what I was thinking too! Thank you for confirming :)

- - - Updated - - -

Btw what is that website you simulate with?
 

BradtheRad

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Yes that was what I was thinking too! Thank you for confirming :)

- - - Updated - - -

Btw what is that website you simulate with?

I used Falstad's animated simulator at:

www.falstad.com/circuit

You can download his Java applet and a library of circuits.

This link opens the website and loads my first circuit. It will run on your computer:

https://tinyurl.com/8fg8kqs

This link will load the second circuit:

https://tinyurl.com/9v2em74

You can save a circuit by selecting the File menu, then 'Export'. Copy the entire text and paste into a text document.
 

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