Which 7 Segment Display is Better: Common Anode or Common Cathode?

When choosing between a common anode or common cathode 7-segment display, the decision should be based on your specific application and circuit design preferences. Each type has its own advantages and disadvantages that can impact the simplicity and efficiency of your design. Below, we will explore the differences, key considerations, and guidance to help you make an informed decision.

Common Anode 7-Segment Display

Configuration: All the anodes of the LED segments are connected together and to a positive voltage.

Control: To turn on a segment, a low voltage ground is applied to the corresponding cathode pin.

Advantages

Simpler interfacing with active low logic, such as microcontrollers that output low to turn on. Can be more intuitive when designing circuits that require multiple segments to be lit simultaneously.

Disadvantages

Requires more complex driving circuitry if the logic levels are high.

Common Cathode 7-Segment Display

Configuration: All the cathodes of the LED segments are connected together and to ground.

Control: To turn on a segment, a high voltage positive is applied to the corresponding anode pin.

Advantages

Simpler interfacing with active high logic, such as microcontrollers that output high to turn on. Generally easier to use with standard logic levels as many microcontrollers output high to turn on components.

Disadvantages

Can be less intuitive when needing to light multiple segments simultaneously with active low logic.

Conclusion: Choosing the Right 7-Segment Display

Based on the above, here is a summary of when to choose each type:

Choose Common Anode: If your design primarily uses active low logic or if you prefer the intuitive approach of connecting the anodes to a positive voltage. Choose Common Cathode: If your design uses active high logic or if you want simpler integration with logic circuits that output high.

Ultimately, both types can be used effectively with the right circuit design. However, it often comes down to personal preference and the specific requirements of your project.

Driver Circuit Simplification

Neither type is inherently better; the choice is generally based on simplifying the driver circuitry and minimizing overall circuit cost. Here are some additional considerations:

When Digits Are Not Multiplexed: Common cathode displays are better because you need 7 or 8 cathode drivers per digit and one anode driver. When Digits Are Multiplexed: Less than 7-8 digits: Common cathode is better. More than 8 multiplexed digits: Common anode is better, requiring 7 or 8 anode drivers and a cathode driver for each digit.

By understanding these differences and considerations, you can make a well-informed decision that simplifies your circuit and optimizes performance for your specific application.