powerRGB
powerRGB is the extension of tinyRGB to drive high power LED’s. For this project I used a 3 x 1W common Anode RGB LED.
Q1 to Q3 are N-Channel HEXFet Mosfet’s with logic level drive and a RDSon at about 50mOhms. R1 to R3 are at about 2k2, R4 to R6 at about 15k and R7 to R9 depend on the LED used and VCC. If you use FET’s with higher RDSon you have to consider RDS in your calculation!
Rx = (Vcc-Vf)/Im – RDSon
[Vcc: Volatge of power supply, Vf: Vorward Voltage of the Diode, Im: Max current of LED]
The software for the AVR is the same as for tinyRGB.
December 21st, 2006 at 12:54
[...] If you want to control power LED’s read here: powerRGB. [...]
February 5th, 2007 at 07:24
Can you provide some part # for the MOSFET that will work with powerRGB? I’m not all that familiar with them, and a stab at Digikey’s search function didn’t return anything useful. Thanks.
BTW, I find this a much simpler circuit than others I’ve seen, and I like the extensibility to cover higher power RGB. Thanks for posting!
February 5th, 2007 at 09:38
Hi,
any N-Channel, Enhancement, Logic level MOSFET should be o.k. You should also select some with low Rds_on. For the STORM hack I used some IRL3103 ( http://www.irf.com/product-info/datasheets/data/irl3103.pdf ).
Hope that helps… Tobi
February 22nd, 2007 at 08:38
Why you have those R4 to R6 + Vcc connections? This would work better without them.
February 22nd, 2007 at 19:44
I had problems with some MOSFET’s and with the resistors it worked well…
Leave at least the series resistor (r1-r3) to limit gate charge currents.
March 5th, 2007 at 19:10
Hello Tobi,
which RGB LED you’ve used and where you bought the led? the only RGB LED I find here is the http://www.led1.de/shop/product_info.php?pName=prolight-power-rgb-led-3-watt-ga-p-308&cName=prolight-power-leds-prolight-power-rgb-leds-c-8_73
March 15th, 2007 at 01:34
The one shown in the link is o.k. for powerRGB. I bought mine via Ebay from a Seller in China.
January 31st, 2009 at 20:34
[...] angesteuert und verpackt w�¤ren. Nach etwas recherche schien es mir am einfachsten ungef�¤hr diese Schaltung nachzubauen. Allerdings w�¤hlte ich einen anderen Mikrocontroller (AtTiny25). Eine Farnell [...]
February 19th, 2009 at 21:42
Bit late but, wouldnt it be better if you deleted R1,R2 and R3??
And R4,R5,R6 to ground!
Explanation: The mosfet doesn’t need any resistance in the gate because it is voltage controlled.
But the resistors to the ground are needed bacause when the pin of your AVR will become 0V, the gate voltage will try to run trough your avr. Simply prevented with the pulldowns.
Is this making any sense? I’m making a similar project as we speak. Any other useful tips for me?
greets,
Sven
February 19th, 2009 at 22:22
changed it…
February 19th, 2009 at 22:29
Another thing. Where do you get that Rds on = 50mOhm from?? in datasheet i find 1.8 – 5 Ohm.
greets,
Sven
February 19th, 2009 at 22:30
Wow you answered fast! Does this mean its all true what i’ve said?
February 19th, 2009 at 22:42
Above i wrote that I tried some MOSFET’s and i forgot always to update to schematics. For the type of MOSFET drawn and mentioned here that updated schematics makes more sense. The RDSon is just an approximate value. See figure 1 in the datasheet. For Vgs & Vds at about 5V the diagram states about 100A which would lead to 50mOhms. But needer Vgs nor Vds are at 5V, but I think that the 50mOhm are a good choice.