What is the Difference Between Common Anode and Common Cathode?

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The main difference between common anode and common cathode in LED displays lies in the arrangement of the LED components and the direction of the current flow. Here are the key differences:

  • Common Anode: In this configuration, all the anodes of the individual LEDs are connected together and to a common terminal, while the cathodes of each LED are connected separately. The current flow direction in common anode mode is from the PCB to the LED diodes.
  • Common Cathode: In this configuration, all the cathodes of the individual LEDs are connected together and to a common terminal, while the anodes of each LED are connected separately. Common cathode displays are also known as "energy-saving LED displays".

The choice between common anode and common cathode depends on the specific application and desired display characteristics. For example, common cathode displays are often used when energy efficiency is a priority, as they can reduce power consumption. On the other hand, common anode displays may be preferred when the display requires a more complex component layout on PCBs.

Comparative Table: Common Anode vs Common Cathode

The main difference between common anode and common cathode 7-segment displays lies in the connection of the LED segments' anodes and cathodes. Here is a comparison table highlighting the differences:

Feature Common Anode Common Cathode
LED Segments Anodes connected together, cathodes connected separately Cathodes connected together, anodes connected separately
Driver Requirement Driver with outputs that go low to turn each segment on Driver with outputs that go high to turn each segment on
Pinout Anode pins connected together, cathode pins separate Cathode pins connected together, anode pins separate
Power Direction Power flows from the PCB to the LED diodes Power flows from the LED diodes to the PCB
Voltage Level Positive voltage applied to the anode Negative voltage applied to the cathode

Common anode displays have all the LED anodes connected together and need a driver with outputs that go low to turn each segment on. On the other hand, common cathode displays have all the LED cathodes connected together and need a driver with outputs that go high to turn each segment on.