Understanding ADC Voltage Measurement with a 10-bit Resolution

Introduction

For many electronic systems, accurate voltage measurement is crucial. This often involves the use of Analog-to-Digital Converters (ADCs). In this article, we will explore the process of measuring a 5V DC voltage using a 10-bit ADC. We will delve into the formula and details necessary to calculate the measured voltage from the ADC value.

ADC Basics

ADCs convert analog signals to digital signals. A 10-bit ADC, for instance, provides 1024 (210) discrete levels to represent a voltage within a specified range. The maximum value that an ADC register can return is 1023, as the range starts from 0.

Measuring Voltage with a 10-bit ADC

Suppose we are measuring a 5V DC voltage with a 10-bit ADC and the ADC returns a value of 300. To calculate the measured voltage, we can use the following formula:

[ text{Measured Voltage} left(frac{text{ADC Value}}{text{Max ADC Value}}right) times text{Reference Voltage} ]

Maximum ADC Value

For a 10-bit ADC, the maximum ADC value is:

[ text{Max ADC Value} 2^{10} - 1 1023 ]

Calculating the Measured Voltage

Given:

ADC Value 300 Reference Voltage 5V

Substituting the values into the formula:

[ text{Measured Voltage} left(frac{300}{1023}right) times 5V approx 1.465V ]

Therefore, the measured voltage is approximately 1.465V.

Potential Pitfalls and Clarifications

Some important points to note:

The voltage range that the ADC measures is dependent on the reference voltage. In the context of 5V DC, the reference voltage in this case is 5V.

0 on the ADC corresponds to 0V, and 1023 corresponds to 5V. Hence, 300 on the ADC would correspond to:

[ 5V times frac{300}{1023} approx 1.466V ]

We need to know the full-scale range (FSR) or reference voltage for the ADC and potentially other factors such as noise, INL (Integral Non-Linearity), and DNL (Differential Non-Linearity) for a more accurate measurement.

If we are measuring a full scale of 5V and the ADC value is 300, the calculation would be:

[ text{Full Scale Voltage} 5V times left(frac{1023}{1024}right) approx 5.000V ]

The accuracy of the measurement depends on factors including the reference voltage, input attenuation, and the accuracy of the divider resistors.

Conclusion

To accurately measure voltages using an ADC, it is essential to understand the reference voltage, the scale of the ADC, and any applicable specifications such as INL and DNL. The formula provided gives a good starting point, but additional details are necessary for precise measurement.