Dual color LED help save space: instead of using a separate green and a red LED, for example, a single bi-color LED can indicate both states by changing its color. They exist in any available LED color combination.
Two LED with different colors
What sets them apart is that internally, they use two separate LED with different colors. It’s essentially a 2-in-1 package.
You could as well use a RGB LED to show different colors. For indicator purposes where just two states matter, dual color LED are simpler (and cheaper).
Identifying Anode and Cathode
The middle pin serves either as common anode (+) or common cathode (-), depending on LED type.
The other two pins connect to the respective internal LED, one per color.
You control both colors individually and can power them individually or at the same time, essentially mixing colors: the LED therefore can display three different colors.
The forward voltage depends on LED color. Since both internal LED display different colors, their specs are different, too. You need different series resistors for each of the two internal LED.
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(content created Mar 01, 2024 - last updated Mar 18, 2024)