Quick answer
LED connections include direct, common anode, and common cathode methods. Common anode wiring joins the positive sides of multiple LEDs together. These different connection types are necessary for various product applications.
When you use LEDs in a product, the most common wiring methods are common anode and common cathode. However, there is a third, less-known method. This article will explain all three common connection types and why these different methods are necessary. We’ll also provide examples for each.
Table of Contents
The Three most common LED connection methods
There are about four main ways to connect LEDs in products, and here are the three most common ones:
- Direct configuration
- Common anode configuration
- Common Cathode configuration
Direct configuration
The Direct Configuration is the most basic way to light up an LED. For an LED to turn on, you just need to meet four simple conditions:
- A higher voltage connects to the LED’s positive (+) side.
- A lower voltage connects to the LED’s negative (-) side.
- The voltage difference is slightly higher than the LED’s forward voltage (if the voltage is too high, the LED will burn out).
- The current flowing through the LED is less than its maximum limit (if the current is too high, the LED will burn out).
This method is simple. You just control the voltage difference to be a little bit more than the LED’s forward voltage, and it will light up easily. If the voltage difference is too large, you’ll need to use a current-limiting resistor in the circuit to prevent the LED from burning out. You can learn more about how to design a current-limiting resistor in this article.
Common Anode configuration
Common anode is a way to connect multiple LEDs together. It works by connecting the positive (+) side (anode) of several LEDs to a single point.
For example, look at the circuit diagram for the OPS-S4010SE-GW above. It connects the anodes of eight LEDs (labeled A-G and Dp) together. The negative (-) side (cathode) of each LED is connected to its own separate output pin.
The principle for lighting up a common anode LED is the same as the direct configuration: you just need to apply the correct voltage across the LED. If the voltage is too high, you’ll use a current-limiting resistor in the circuit to prevent the LED from burning out. The resistor and the LED can be placed in either order and will still work correctly
Common Cathode configuration
Common cathode is a way to connect multiple LEDs by joining the negative (-) side (cathode) of several LEDs to a single point.
For example, the circuit diagram for the OPS-S4011SE-GW shows the cathodes of eight LEDs (labeled A-G and Dp) connected together. The positive (+) side (anode) of each LED is connected to its own separate output pin.
Just like with the direct configuration, you light up a common cathode LED by applying the correct voltage across it. If the voltage is too high, you must use a current-limiting resistor to prevent the LED from burning out. The resistor and the LED can be placed in either order and will still work correctly.
Why Do We Have Fixed LED Connection Methods?
There are two main reasons for using fixed LED connection methods like common anode or common cathode:
- To reduce the number of wires and connections.
- To be able to light up each LED individually.
For example, a common anode seven-segment display uses fewer external pins than a direct connection method. If you used a direct connection, you would need more pins, which would waste space on the circuit board (PCB). By using a common anode or common cathode setup, you can still light up each LED individually while keeping the number of pins and the overall size of the module smaller. This is why these connection methods are used so often in LED products.
The three most common LED connection methods
| Method | How it is connected | Note |
|---|---|---|
| Direct configuration | Higher voltage to (+), lower voltage to (−), with the voltage difference slightly above the LED’s forward voltage | The most basic way to light a single LED |
| Common anode | Positive (+) sides of multiple LEDs joined to a single common point | Groups multiple LEDs |
| Common cathode | Negative (−) sides of multiple LEDs joined to a single common point | Groups multiple LEDs |
Conclusion
The Direct Configuration is great for lighting up a single LED, but when a product has many LEDs, using the Common Anode or Common Cathode methods is better. These methods reduce the number of output pins while still allowing you to light up each LED individually using the same direct-lighting principle.
Opto Plus is a Taiwan LED manufacturer operating since 2009. We produce a wide range of standard products with both common anode and common cathode connections, including:
SMD and THT 7-segment displays
SMD and THT alphanumeric displays
SMD and THT dot matrix displays
We also offer custom-made SMD and THT LED displays. If you have any needs, feel free to contact us at Sales@opledtw.com or through our contact form.
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FAQ
What are the three most common LED connection methods?
－Direct Configuration: The most basic way to light up a single LED.
－Common Anode Configuration: A method where the positive (+) side of multiple LEDs are connected together.
－Common Cathode Configuration: A method where the negative (-) side of multiple LEDs are connected together.
No matter how you connect it, to light up an LED, you must meet these four basic conditions:
－The positive (+) side of the LED needs a higher voltage.
－The negative (-) side of the LED needs a lower voltage.
－The voltage difference between the two sides must be slightly more than the LED’s forward voltage (too much voltage will burn it out).
－The current flowing through the LED must be less than its maximum limit (too much current will burn it out).
Common anode configuration is a way of connecting multiple LEDs by joining all their positive (+) sides (anodes) to a single point.
In this setup, all the LED anodes share one common connection, while the negative (-) sides (cathodes) are each wired to their own separate pin. To light up a specific LED, you just need to apply the correct voltage to its individual cathode pin.
Common cathode configuration is the opposite of common anode. In this method, the negative (-) sides (cathodes) of multiple LEDs are connected together to a single point.
All the LED cathodes share one common connection, while the positive (+) sides (anodes) are each wired to their own separate pin. To light up a specific LED, you need to apply the correct voltage to its individual anode pin.
LED products use common anode or common cathode connections mainly for two reasons:
－To control each LED: These common connections still let you turn on each individual LED separately, using the same direct-lighting method.