Summary of RGB LED PWM Driver for High Power 350mA LEDs using PIC12F629
This project is an RGB LED controller using a PIC12F629 and three constant-current buck converters to drive high-power 350mA LEDs with PWM, enabling fades, strobe and up to 16 million colours. Surface-mount construction yields a compact board that can drive one or two LEDs per channel; example mood-light assembly used a Homebase fitting, custom copper heat spreader and simple mounting. Compatible parts include Zetex ZXLD1350/ZLLS1000 and several Panasonic and Sumida inductors; sequence code is compatible with other standalone RGB controllers on the site.
Parts used in the RGB LED PWM Driver for High Power 350mA LEDs using PIC12F629:
- PIC12F629 microcontroller
- Zetex ZXLD1350 constant current buck converter
- Zetex ZLLS1000 constant current buck converter
- Surface mount components (resistors, capacitors, etc.)
- Inductor Panasonic ELL6RH680M (or listed alternatives)
- Panasonic ELL-6PM680M (possible alternative)
- Sumida CR54NP-680KC 68µH inductor (possible alternative)
- Sumida CDPH4D19FNP-470MC 47µH inductor (possible alternative)
- Sumida CDRH6D28NP-820NC 82µH inductor (possible alternative)
- Sumida CDRH6D28NP-101NC 100µH inductor (possible alternative)
- RGB high-power 350mA LED (from suppliers such as led-bulbs.com)
- DC power connector and mounting hardware (eg M2.5 screws)
- Mode switch
- Copper heat spreader (made from copper plumbing pipe) or heatsink
- PCB (surface-mount assembled)
Description
This project combines a PIC and three constant current ‘buck’ converters to produce an RGB LED controller that will operate with the the high power 350mA LEDs using PWM to control the LED brightness. By driving the red, green and blue LEDs with varying pulse widths the controller can generate up to 16 million colours using fades, strobe and static effects.
The use of surface mount components and the low power dissipation in the three current sources allows for a very compact design.
The circuit can drive one or two LEDs in each of the three channels and will work with devices from Luxeon, Prolight, Laminar, Lumileds and others.
The project uses a slightly modified version of the code used for the Standalone RGB controller described elsewhere on this site allowing the sequence data file to be used from the other controllers.
As the board uses surface mount components this project is not really suitable unless you have the soldering skills and experience to work with this technology.
Mood Light
Here we have a mood light made using the circuit described on this page and a light fitting I bought from Homebase DIY store. It’s a 26cm metal rim flush light fitting with brushed chrome finish. The frosted glass dome diffuses the light from the LEDs while the silver metal base helps distribute the light evenly.
Assembly was kept very simple. A hole was drilled in the base for the ‘mode’ switch to fit through and the PCB was fixed down with double sided tape. Another hole was drilled and then filed square for the DC power connector which was secured with two M2.5 screws. The RGB LED came from www.led-bulbs.com It wasn’t fitted to a heatsink so one was made from a piece of copper plumbing pipe cut open and flattened; the heat spreader in the base of the LED was then soldered to the copper. When the whole assembly is screwed to the metal body of the lamp fitting it provides excellent heat dissipation for the LED.
Once assembled it can be fixed to the ceiling, hung from a wall or simply placed on top of a table or other furniture. If it’s placed on a flat surface at eye level when you’re sitting down, the low profile of the fitting illuminates upwards without being too obtrusive and the overall effect is very pleasing.
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The Zetex ZXLD1350 and ZLLS1000 parts are available from Farnell and Digi-Key
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Inductor Panasonic Part No: ELL6RH680M, Farnell Order Code: 1198602.
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The inductors listed below appear to be suitable on specification only, I have not tried them.
Panasonic
ELL-6PM680M, Digi-Key part No PCD1714CT-NDSumida
68µH Digi-Key part No 308-1536-1-ND CR54NP-680KC
47µH Digi-Key part No 308-1316-1-ND CDPH4D19FNP-470MC
82µH Digi-Key part No 308-1501-1-ND CDRH6D28NP-820NC
100µH Digi-Key part No 308-1488-1-ND CDRH6D28NP-101NC
For more detail: RGB LED PWM Driver for High Power 350mA LEDs using PIC12F629
- What microcontroller does the project use?
The project uses a PIC12F629 microcontroller. - Can this controller drive high power 350mA LEDs?
Yes, it is designed to drive high power 350mA LEDs using three constant current buck converters. - How many LEDs can each channel drive?
Each of the three channels can drive one or two LEDs. - Does the project support colour fades and strobe effects?
Yes, PWM is used to provide fades, strobe and static effects and up to 16 million colours. - Are surface mount skills required to build the board?
Yes, the board uses surface mount components and is not suitable unless you have soldering skills and experience with SMD. - Which constant current converter parts are recommended?
The Zetex ZXLD1350 and ZLLS1000 parts are referenced as available from Farnell and Digi-Key. - What inductors are specified for the design?
The inductor Panasonic ELL6RH680M (Farnell 1198602) is listed, with several Panasonic and Sumida alternatives given. - Can the sequence data file be shared with other controllers?
Yes, the project uses a slightly modified version of code allowing the sequence data file to be used from the other standalone RGB controller on the site. - How was heat dissipation handled in the mood light example?
A copper heat spreader made from plumbing pipe was soldered to the LED base and when mounted to the metal lamp body provided excellent heat dissipation. - Where was the RGB LED for the mood light sourced?
The RGB LED used in the mood light example came from led-bulbs.com.
