Analog vs Digital Potentiometer - Differences and Advantages

This page compares Analog Potentiometer (Pot) vs. Digital Potentiometer (Pot) and mentions the difference between them. An analog pot is also known as a mechanical potentiometer, and a digital pot is known as an electronic potentiometer due to their construction. It also mentions the benefits or advantages of these potentiometer types.

Introduction

A potentiometer is a three-terminal device with a rotating or sliding contact that forms an adjustable voltage divider. It functions as a variable resistor or rheostat when two terminals are used (one end and wiper). Potentiometers have a wide variety of applications such as volume or tone controls in audio systems, and as position sensors (or transducers) in joysticks, etc.

Analog Potentiometer (Mechanical Potentiometer)

Figure 1: Analog or Mechanical Potentiometer

• The figure above depicts an analog or mechanical potentiometer. It consists of a resistive element with a sliding contact that can be rotated manually by hand.
• As shown, there are three terminals. Between two of the terminals, there is a resistive element. The third one, the wiper, is connected across various points along the resistive element.
• In this pot type, the wiper is physically moved by hand. The three terminals are +5V, Measure, and GND. The “Measure” and “GND” terminals provide variable voltage when the wiper is moved or rotated.
• Due to its construction and function, analog potentiometers are called mechanical potentiometers.

Advantages:

• Simple
• Inexpensive
• Compact
• Used as a digital gain control

Digital Potentiometer (Electronic Potentiometer)

Figure 2: Digital or Electronic Potentiometer

• The figure above depicts a digital or electronic potentiometer. It consists of an interface, control, and registers.
• Input signals to the digital section are external control signals from a serial bus. Outputs from the digital section are internal signals stored in internal volatile and nonvolatile registers or signals that move the wiper. Nonvolatile digital pots can retain resistance value regardless of external conditions.
• In this pot type, the wiper is digitally controlled either by a computer, microcontroller, or microprocessor. The resistance between two terminals can be adjusted using these digital input signals, similar to an analog potentiometer.
• Serial buses can be either asynchronous or synchronous. The most common asynchronous interface bus is an increment/decrement interface (U/D’, INC’, CS’). The most common synchronous interface bus is I2C, SPI, Two-wire, microwire, etc.
• The common signals are clock, data-in, data-out, control, and address.
• Due to its construction and function, digital potentiometers are called electronic potentiometers.
• Examples of digital potentiometers: MAX5427/MAX5428/MAX5429 linear digital potentiometers from Maxim Integrated, AD5171 (I2C controllable) and AD5206 (SPI controllable) from Analog Devices Inc.

Advantages of digital potentiometers compared to analog potentiometers:

• More reliable compared to mechanical potentiometers
• Space savings
• Wide range of resolution
• Insensitive to harsh environments
• Available in volatile and non-volatile types
• Much more writing cycles than mechanical parts