AN629
DIGITAL POTENTIOMETERS
Jul 01, 2001
Digitally Adjustable Voltage References
A digitally adjustable voltage reference is useful in many applications. For instance, it can be used to finely tune the reference voltage when absolute accuracy is required or to adjust the reference voltage to match the full-scale voltage range of an analog-input signal to maximize the dynamic range of an analog-to-digital conversion. You can easily create one by bining an adjustable voltage reference with a digital potentiometer (pot). Using the digitally variable aspect of the digital pot to control the adjustment voltage on the reference results in a flexible and useful circuit. Three basic circuit topologies are presented here. The first achieves a coarse adjustment over a wide voltage range, the second a fine adjustment over a narrow voltage range, and the third a fine adjustment over a wide voltage range. These simple circuits can be used directly or can form the basis for more plex control systems....
