RGB LED Selection

Question

Problem: RGB LED Selection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose

An RGB LED combines red, green, and blue LED dies in a single package. By turning different dies ON, the MCU can show multiple colors from one component: red for fault, green for normal, blue for communication. Mixing colors (e.g., red + green = yellow) gives even more states.

A common cathode configuration means all three dies share one ground pin, and each color has its own anode pin — 4 pins total. The MCU drives each anode through a separate series resistor.

The 5050 package (5mm × 5mm) is a standard SMD RGB LED size with good brightness and well-defined pinout.

Required: RGB · Common Cathode · 4-Pin · 4-SMD· SMD · 20mA per color · −40°C to +85°C · RoHS

2. How to Find It on DigiKey

Go to DigiKey.com → Optoelectronics → LED Indication - Discrete

Apply these filters:

Color → Red, Green, Blue (RGB)
Configuration → Common Cathode
Package / Case → 4-SMD
Mounting Type → Surface Mount
Part Status → Active

Important: Common Cathode and Common Anode are NOT interchangeable. Common Cathode has shared ground (MCU sources current to each color). Common Anode has shared VCC (MCU sinks current). The circuit design must match. This task requires Common Cathode.

3. Key Specifications & What They Mean

Specification	Required	Why
LED Type	RGB	Three colors in one package.
Configuration	Common Cathode	Shared ground; individual color anodes.
Pins	4	1 cathode + 3 anodes (R, G, B).
Package	4-SMD	Standard 5mm×5mm RGB LED size.
Test Current	20mA per color	Standard brightness per die.
Temp Range	−40°C to +85°C	Industrial operating conditions.
RoHS	Yes	Compliance required.

Tip: Each color has a different forward voltage. Red is typically 1.8–2.4V; green and blue are 2.8–3.4V. You need a separate series resistor for each color, calculated using its specific Vf.

4. Selecting a Safe, Production-Ready Part

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

5. Filtered DigiKey Link

➡ View Matching Parts — RGB, Common Cathode, 4-Pin, 5050, SMD

41. RGB LED Selection