LEDLIGHTING
RGB LED Colour Mixing
A single LED die can only emit monochromatic light which could be one of the three primary colors - red, green and blue, known as RGB. To realize more colors, three LED dies need to be used together for RGB color mixing. Commonly 7 colors can be produced by controlling the switch of the channel for each primary color. To produce more than 7 colors, each color channel should be able to change in brightness, not just switched on or off. A popular control method is PWM, of which the cycle duty range determines the available brightness levels. The more the levels are available, the more colors can be produced. Apart from the popularity in applications like outdoor decoration lighting in cities, stage lighting designs, home decoration lighting and LED display matrix, RGB color mixing technology can also be found recently in LCD backlighting and projectors.
To implement different patterns of RGB color mixing, each LED die needs a dedicated signal for dimming. One method is using a single driver that has three or more channels and is capable of controlling each channel separately for dimming. The other is using three drivers to provide power and implement dimming function respectively on three channels. Obviously, the former method uses fewer drivers and is suitable for the applications such as backlighting and display matrix that work on lower current and a large number of LEDs. The latter one can be used in high power applications such as decoration lighting.
In addition, a MCU is required to drive LED driver to carry out dimming function and store color configurations of LEDs. For those applications that require more accurate color mixing, color and temperature sensors should be used to monitor the mixed color output and provide feedback.
LEDs used in RGB color mixing are totally depends on application requirement, either High Brightness or High Power LEDs can be used in these applications. The main suppliers include Cree, Broadcom, Lumex and Vishay. LED driver are available from National Semiconductor, ON Semiconductor, TI and Linear Technology.
Hover over the diagram blocks to view recommended products for this solution:
Used for the control and dimming of LEDs, storing the color configurations of LED and receiving the feedback from sensor.
ATMEL
MICROCHIP
Providing constant current to LEDs. Designers can use either one driver that has three channels or three drivers with single channel to implement dimming function for each single-color LED.
LINEAR TECHNOLOGY
NATIONAL SEMICONDUCTOR
It can be three color dies packaged in one LED or three single color LEDs
BROADCOM
Luxeon
Osram
Detecting the composition of the three primary colors after mixing, and sending result back to MCU
BROADCOM
BROADCOM
Monitoring the temperature and sending signal back to MCU, to ensure a stable output in a wider temperature range
ANALOG DEVICES
TEXAS INSTRUMENTS
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 | AC164133 - Buck/Boost Converter PICtail Plus Microchip The Buck/Boost Converter PICtail™ Plus Daughter Board provides an easy and economical way to evaluate Switch Mode Power Supply applications with the dsPIC33F GS Digital Power Conversion family. | |
 | DM330014 - LED Lighting Development Kit Microchip Microchip's Digital LED Lighting Development Kit enables designers to quickly leverage the capabilities and performances of the dsPIC33F GS series of Digital Signal Controllers (DSCs) to develop LED-lighting products. | |
 | MCP1630 Boost Mode LED Driver Demo Board Microchip The MCP1630 Boost Mode LED Driver Demo Board is a step-up, switch-mode, DC-DC converter used for power LED applications. | |
 | MCP1650 3W White LED Demo Board Microchip The MCP1650 3W White LED Demo Board demonstrates Microchip’s MCP165X Boost Controller product family in a battery powered white LED application. | |
 | MCP1650 Multiple White LED Demo Board Microchip The MCP1650 Multiple White LED Demo Board uses the MCP1650 IC to power the nine white LEDs which are connected in series. | |
 | TMDSDCDCLEDKIT - DC-DC LED Developer's Kit Texas Instruments The kit is based on the Piccolo MCU and the controlCARD platform. One Piccolo MCU is able to directly control eight separate DC/DC power stages as well as up to eight LED strings of various LED types and string lengths. | |
| Image | Description |
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| MICROCHIP | PWM Controller | Dimming Power LEDs Using a SEPIC Converter and MCP1631 | AN1261 Apps Note | Click here | |
| Manufacturer | Product Type | AN Title | AN Number | Part Number | URL |
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| CREE | LED | Cree Binonator Tool for Chromaticity and Flux Mixing | Click here |
| Manufacturer | Product Type | White Paper Title | URL |
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| TEXAS INSTRUMENTS | LED Driver | Three-Color LED Driver Evaluation Module (EVM) | TPS62260LED-338 | TPS62260 | Click here |
| NATIONAL SEMICONDUCTOR | LED Driver | LP5521TM Evaluation Kit | LP5521 | Click here | |
| MICROCHIP | LED Driver | DM240001 Explorer 16 Development Board | DM240001 | PIC24FJ128/dsPIC33FJ256 | Click here |
| Manufacturer | Product Type | Evaluation Kits Title | EVKs Part Number | Part Number | URL |
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| TEXAS INSTRUMENTS | LED Driver | TPS62260LED-338: Color Lighting Innovations with a New LED Board | Click here | |
| Cree | HP LED | XLamp® Color LEDs | Click here | |
| Manufacturer | Product Type | Training Title | Part Number | URL |
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