Digital Potentiometers: Advantages and Disadvantages

This page explores the advantages and disadvantages of digital potentiometers compared to their analog counterparts.

What is a Digital Potentiometer?

Introduction:

• A digital potentiometer is a mixed-signal device that allows for digital control of a variable voltage.
• It’s essentially an IC chip designed to emulate the function of an analog potentiometer.
• It’s digitally programmable, meaning its internal resistance can be adjusted using input controls. This makes it ideal for use with microcontrollers to precisely control the component’s internal resistance.

Analog Potentiometer

Digital Potentiometer

• As shown in the figure above, a digital (or electronic) potentiometer consists of an interface, control logic, and registers. Input signals to the digital section are external control signals received from a serial bus. Outputs from the digital section are internal signals stored in internal volatile and nonvolatile registers, or signals that control the wiper position.
• These potentiometers often offer interface buses like I2C, SPI, Two-wire, and microwire, allowing control through a variety of interfaces.
• The wiper is digitally controlled, typically by a computer, microcontroller, or microprocessor. Similar to an analog potentiometer, the resistance between two terminals can be adjusted using these digital input signals.
• Digital potentiometers are available in both volatile and non-volatile memory types. (Refer to “Analog Potentiometer vs. Digital Potentiometer” for a detailed comparison.)

Benefits or Advantages of Digital Potentiometers

The following are the benefits or advantages of using digital potentiometers:

• Increased Reliability: They are significantly more reliable than mechanical or analog potentiometers. Digital pots are rated for as many as a million cycles, compared to only a few thousand for their analog counterparts.
• Digital Interface: They offer a convenient digital interface.
• Smaller Size: Digital potentiometers are smaller and can be placed very close to other chips on the board. This eliminates long signal paths and saves space. Reducing the signal path length also minimizes capacitive effects.
• Lightweight: They are small in size and also less in weight.
• Wide Range of Resolution
• Insensitivity to Harsh Environments
• Higher Writing Cycles: They offer significantly more writing cycles than mechanical parts.

Drawbacks or Disadvantages of Digital Potentiometers

The following are the drawbacks or disadvantages of digital potentiometers:

• Temperature Sensitivity: Their internal resistance can be affected by variations in temperature.
• Limited Current Handling: They are not designed for high-current applications. While some digital pots can source or sink more than 20 mA at the output, 1mA is more typical.
• Less User-Friendly: They are not as user-friendly as analog potentiometers due to the lack of a physical knob.