A resistive feedback network is often used to set the output voltage of a power supply. While a mechanical potentiometer (pot) conveniently solves the problem of adjusting a power supply, it can be replaced with a digital pot for easier automatic calibration.
This article presents a calibration solution that uses a digital pot, because pots are smaller, do not move with age or vibration, and can be recalibrated remotely. This proposed solution reduces the susceptibility of the system to the tolerance of the digital potís end-to-end resistance, making the solution optimal for designers.
The article also explains some of the equations required to calculate the resistor chain values and to use a digital pot in this way. Also, a spreadsheet with standard resistor values is available for easy calculations.
"Calibrate a power supply with a digital potentiometer" is presented in its entirety as a pdf document, for convenience.
About the Author
David Fry is the Strategic Applications Manager for the DACs, pots, and references product line at Maxim Integrated Products. He has over 25 years experience in the electronics industry, with the last 13 years working in semiconductor field applications, market development, and product-line applications. Prior to joining Maxim, David spent 11 years as a board-level designer working on RF designs and several years designing high-end broadcast video equipment. He earned a BSc in Electronics in 1984 from the University of Manchester Institute of Science and Technology.
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