A Hands-On Look at Three High-Resolution ADCs

In this article Brian takes a close look at three different high-resolution ADCs and compares their features, strengths, and more. Two of the three devices have shown up in his past projects and he anticipates using the third in the future.

- Brian Millier

While it is somewhat of a moving target, to be considered a high-resolution analog to digital converter (ADC), a device generally had to have a resolution of 16 bits or greater. Currently, many ADCs are available with 16-bit resolution, and 20+ bits could now be considered the norm for the high-resolution designation. Of course, the higher the sample rate of an ADC, the harder it is to achieve high-resolution. In this article, I will be describing ADCs with sample rates in the hundreds to thousands of samples per second, as that is what I generally need in my projects. In this speed range, it is quite common for such ADCs to include a Programmable Gain Amplifier (PGA) and maybe a multiplexer to expand the number of channels that can be measured. When such features are built in, the device may be called an analog front end (AFE) instead of an ADC, so if you are doing a search for high-resolution ADCs on your distributer's website, you may want to search on this term as well.

THE CONTENDERS

Here are the three ADCs that I will be discussing in this article:

• ADS1115 16-bit ADC with PGA and 4-channel multiplexer (Texas Instruments)

• NAU7802 24-bit ADC with PGA and 2-channel multiplexer (Nuvoton)

• MCP3910/3911 24-bit dual ADC with dual PGA (Microchip)