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3.3V sensor to 5V ADC

sciguy14

Nov 23, 2009
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Nov 23, 2009
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Hi there!

I have some 3.3V sensors with analog outputs that I would like to interface to a 5V ADC converter, while maintaining full resolution. ie, I don't want to just give up the range of digital values generated between 3.3V an 5V. An example of one of these sensors is a 3 axis accelerometer, with an analog output for each axis. You can view the data sheet here:

The ADC expects a value between 0 and 5V volts (analog), so if I just send in the 3.3Vmax signal, I'll be wasting valuable resolution. How can I proportionally amplify the 3.3V sensor output so it ranges from 0 to 5V?

Thanks so much!!!
 

Resqueline

Jul 31, 2009
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Jul 31, 2009
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Looking at the datasheet it doesn't seem to me that it's so accurate that losing 1 bit wold matter very much, unless you're using an 8-bit ADC.
That being said it's just a matter of adding 3 non-inverting op-amps with a gain of 5/3.3=1.515 to the outputs. They must of course be supplied by 5V or more, and they could be made somewhat adjustable to make the MMA accurate before digitizing.
 
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