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Association between analog input voltage and ADC digital code

USB-I/O interface adapter ADC module allows conversion of an analog input signal to the corresponding 10-bit digital number. The result is generated via successive approximation. The analog-to-digital conversion can be represented mathematically as:

where:

  • ADCCode – ADC digital output code;

  • VIn – analog input voltage;

  • VRefHi – upper reference voltage;

  • VRefLow – lower reference voltage.

For more detailed information about the reference voltage see Section 7.3, “Analog Reference Voltage”.

We get much simpler expression when VRefLow is equal to zero:

If VRefHi = 5V and VRefLow = 0, analog-to-digital conversion can be illustrated by the following diagram: