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A project log for +/- 10V to 0-3.3V Translator

Differential Op-Amp Circuit to translate +/-10V DAC signals from test equipment to 0-3.3V for Teensy 3.6 Board

Emach00Emach00 02/13/2018 at 21:302 Comments

Following advice, I used the 3.3V as my bias voltage. Can't quite seem to get it down to 0V but this would work too with minimal additional components. 

Discussions

Emach00 wrote 06/25/2018 at 18:42 point

Rin is there to represent the input series impedance of the ADC. https://www.pjrc.com/teensy/K66P144M180SF5V2.pdf

page 45. Thanks for the suggestion, will definitely simulate it.

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K.C. Lee wrote 06/25/2018 at 16:25 point

Rin = 5K loads the output of the voltage divider, so the amplitude will be a bit lower.  It also changes the DC bias point slightly.  In my circuit, the ADC input has very high DC input impedance.  C1 acts as low pass filter, lower AC impedance and provides charges to the ADC during sampling, so you don't need to have Rin connected.

If you change R4 to 10K (while keeping Rin), the output switch of your circuit will be centered at 1.673V and swing from  33mV to 3.314V  While not perfect, it is probably close enough.

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