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Analog input for microcontroller

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expertengr

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Hi,

The analog signal which I want to sample using microcontroller ASC is between 0.5 V to 1.2V. I would like to use the full range of ADC which is 0 to 4.4 V. I guess there are two methods to do this, in the first method the offset and gain can be adjusted using operational amplifier to cover the full ADC range. In the second method the analog signal has to be read directly and then mathmatically the offset and gain can be ajusted accordinly so that 0.5 V corrosponds to 10 bits 0's and 1.2V corrosponds to 10 bits 1's. Which Method is more appropriate here ?
 

Hi,

The analog signal which I want to sample using microcontroller ASC is between 0.5 V to 1.2V. I would like to use the full range of ADC which is 0 to 4.4 V
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This only can achieved with analog signal conditioning circuit. A differential amplifier circuit can do all this.

****
There are several threads discussing this.

I´ve given circuit examples and calculation examples.

Klaus
 

Increase the input signal range to the full range of ADC. May be by using combination of differential & instrumentation amplifier should work for you.
 

The alternative method, if your microcontroller supports it, it to reduce the full-scale of the ADC to 1.2V. If it has an adjustable Vref that can be reduced, or can accept external Vref, you can leave the input signal alone and make the ADC match it's range, that gives full resolution without signal conditioning or math. Many PIC devices can do this, just configure for external -Ref and +Ref and within the devices operating range, you can scale the ADC to match the input range.

Brian.
 

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