Did you know that at least one voltage reference is used in almost every application? This is because a reference point is typically required somewhere inside the signal chain of a system. Voltage references are most commonly used as a reference for data converters, but they can be used in many other areas such as comparator thresholds and zener diode replacements. We often times only glance over this part due to the deceivingly simple pin count of the device (typically 3-5 pins), but this component could easily become the problem child of a system if it isn’t selected properly.
Figure 1 - Example of a reference’s total error and how it varies depending on the operating conditions.
On top of this there are a ton of references that are out in the market and most of them use statements such as “high precision”, “ultra high precision”, or only put one key performance parameter to describe their parts which really doesn't help us with the selection process.
There are seven parameters which affect the performance of a reference and the dominating parameter varies depending on your operating conditions. In order to help explain these parameters (plus a few extra) and how to compile all the errors to understand what total error value to expect, I’ve compiled all the information into a white paper called “Voltage Reference Selection Basics.” Hopefully this paper will bring back the voltage reference to the simple part that it lends itself to be.
I also recommend that you try out our new WEBENCH® Series Voltage Reference Selector tool. This tool was created based on the calculation methods explained in the white paper to simplify the voltage reference selection process for ADCs. All you have to do is choose an ADC and a full lineup of applicable references will appear in order of performance. There is a dial which will weigh noise, temperature coefficient, or initial accuracy as the main parameter depending on what is most important to you. The tool also lets you select multiple references and visually compare side-by-side the error values along with the power consumption of the devices. Try it out here and let me know what you think.
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