Can a MCU be used as a reference voltage?
Some MCUs have an external pin that allows you to provide a voltage reference of your choosing, but others will simply use the MCU’s supply voltage. This can cause inaccuracy, for example, if the MCU accepts 3.3 V analog inputs to the internal ADC while the V REF for that internal ADC is actually the supply voltage to the MCU or 5V.
Can a power supply change the reference voltage of an ADC?
This can cause inaccuracy, for example, if the MCU accepts 3.3 V analog inputs to the internal ADC while the V REF for that internal ADC is actually the supply voltage to the MCU or 5V. In the end, the power supply, which can reasonably vary by as much as 3%, can cause a fairly significant change to conversion results.
Can a microcontroller use a reference voltage?
For microcontrollers (MCUs) that have integrated (internal) ADCs, you may or may not have control over the reference voltage. Some MCUs have an external pin that allows you to provide a voltage reference of your choosing, but others will simply use the MCU’s supply voltage.
What is the reference voltage for a 10-bit ADC?
The value produced by a 10-bit ADC with a 5V reference and a 3.3V analog input signal (where 3.3V is the highest value measured at the input) would be: (V IN x 1,024) /V REF = (3.3 V x 1,024)/5 V = 675.84 However, the result, if V REF were 3.3 V, rather than 5 V, would be:
Is the reference voltage External to the ADC?
The voltage reference is external to the ADC, and along with an amplifier to drive the reference, contributes to the overall system noise. For microcontrollers (MCUs) that have integrated (internal) ADCs, you may or may not have control over the reference voltage.
Why does the voltage of a V ref vary?
The variability of the voltage supplied to V REF is a large factor in the accuracy of your ADC. Power supplies or voltage regulator outputs can vary for several reasons that can be based on temperature and load fluctuations, and with variations from supply to supply, among other things.