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How to use digital potentiometer to eliminate voltage changes? Xiaobian found some technical posts shared by technical people from the network. If it is suitable to use it, follow it~ Both mechanical potentiometers and digital potentiometers have uncertain end-to-end tolerances. The typical value of end-to-end resistance error of digital potentiometers is 20% to 30%. When digital potentiometers are connected in series with other resistors to form a voltage divider network, the deviation of this resistance value may cause some problems, resulting in voltage variation exceeding the allowable error range. This application note discusses a design method of proportional circuit, which converts resistance deviation into acceptable current variation and can effectively eliminate voltage variation. In the circuit given here, the voltage output depends on the ratio of the potentiometer, and the temperature coefficient can also be well controlled in the design. The direct problem of proportional circuit design is that 3% error may lead to voltage variation between 3V and 4.5V. The basic calculation can be performed by using the block diagram shown in Figure 1. The digital potentiometer is 50k Ω (25% tolerance), R1 is 16.5K (1%), R2 is 100K (1%). The tolerance of 25% of the end to end resistance of the potentiometer is the largest error source in the design. Now consider using different tap resistances for the same calculation. If the potentiometer is 37.5k Ω, the top voltage is 4.46V, and the low voltage is 3.25V; If the potentiometer is 62.5k Ω, the voltage at the top is 4.54V, and the voltage at the low end is 2.79V. In this circuit, due to the large end-to-end resistance deviation of the potentiometer, this basic structure cannot be used to solve the voltage change problem. Two voltage references are introduced into the circuit to control the error and temperature coefficient. The end-to-end absolute deviation of the digital potentiometer will change the circuit current, but will not affect the voltage. The output voltage varies proportionally, only depending on the resistance ratio of the potentiometer tap position. The output voltage of the two references is controlled by feedback, and R2 (25K to 50K) determines the source current of the two references. The bypass capacitance will be discussed in the data manual of MAXIM digital potentiometer, and the capacitance can be increased according to the layout.