Tunable White 2835 SMD LED

The Basic Idea

Think of your LED as having two separate light bulbs inside one small package:

One bulb gives warm light (3000K, like a candle).

The other gives cool light (6500K, like noon sunlight).

To get any color temperature in between, you just need to mix these two lights, just like mixing hot and cold water to get the perfect shower temperature.
If you want warmer light, you turn up the warm bulb and turn down the cool bulb. If you want cooler light, you do the opposite.

The Key Technology: PWM (Pulse Width Modulation)

You can't just use a knob to lower the voltage, because LEDs don't work well that way (they might flicker or change color). Instead, we use a trick called PWM.

PWM means turning the LED on and off very fast - thousands of times per second. Your eyes can't see the flicker, so it looks like the LED is always on, but just dimmer or brighter.

If the LED is on for 90% of the time and off for 10%, it looks very bright.

If it's on for 20% of the time, it looks dim.

By controlling these "on‑time" percentages (called duty cycles) for each of your two LEDs, you can mix them in any proportion.

How to Do It in Practice (Simple Steps)

Get a controller that supports dual‑color (CCT) LEDs
The easiest way is to buy a ready‑made dual‑channel LED driver or a CCT controller (CCT = Correlated Color Temperature). These controllers have two outputs:

Output 1 → connects to your 3000K chip

Output 2 → connects to your 6500K chip
Then you can use a remote, a knob, or a smartphone app to slide the color temperature smoothly from 3000K to 6500K.

If you want to build your own circuit, you need:

A microcontroller (like Arduino) - this is the "brain" that generates two PWM signals.

Two LED driver circuits (one for each color) - these take the PWM signals and properly power the LEDs.

A way to control it - like a potentiometer (knob), Bluetooth, or Wi‑Fi.

You then write a simple program that says:
"When the knob is turned halfway, give 50% PWM to the warm LED and 50% to the cool LED."
That gives you roughly 4750K (the middle).
Turn it more to the warm side → warm LED gets 80%, cool gets 20%.

Important Things to Remember

Use constant‑current drivers, not just resistors, because 2835 LEDs need a stable current to work safely and last long.

Set the PWM frequency above 1 kHz (1,000 times per second) so you don't see any flicker.

Keep them cool - when LEDs get hot, their color and brightness can change, and they may burn out faster. Add a heat sink if needed.

Summary in One Sentence

To get any color temperature you want, just independently control the brightness of the 3000K and 6500K chips using PWM, and mix their light - the more power you give to one, the more that color dominates.

 Guangmai Technology is a professional LED manufacturer established in 2009, specializing in LED packaging and custom LED solutions.

Our main products include SMD LEDs, High Power LEDs, COB LEDs, UV LEDs, IR LEDs, VCSELs, and ceramic substrate LEDs. We offer wavelengths from 200nm to 3000nm for applications such as horticulture lighting, medical devices, industrial curing, machine vision, security, and scientific research.

With advanced production equipment, strict quality control, and experienced engineering support, we provide reliable products and customized solutions to customers in more than 50 countries worldwide.

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