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Author Topic: Powering 200W LEDs  (Read 2102 times)
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Rapa Nui
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..the power mosfets have usualy a large gate capacitance, so you might need a "driver". The driver has to be put between arduino's pwm output and the mosfet's gate.
When not using the driver, the mosfets will be operating in a "linear region" (because the arduino's low output current will charge/discharge the mosfet's gate capacitance rather slowly when switching between logical 1 and 0) and the mosfets might become quite hot. The power dissipation of the mosfets is proportional to on/off switching time (influenced mainly by the gate charge/discharge speed) and the U*I between mosfet's source and drain.
P.
« Last Edit: October 18, 2011, 02:23:04 pm by pito » Logged

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hi
Im not understand what you really want, but if you dont have an Electronic knowloge I recomend you to use power supply whit PWM included.
The image are in spanish but you can deduced


You can increase the PWM voltage range whit this IC


I can you you more option but I need to undertan better your proyect if you draw you led configuration maybe ease to help you.
you can use the IC ULN2003 to drive a led dependig how many milli amp consume.
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Helsingborg, Sweden
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Connected one 9.8W strip directly to the Arduino (connected to 12VDC) tonight. Green and Blue are responding as they should, red is static.... why is that? Why isn´t the PWM-signal sufficient for the red, but for the blue and green? Guess I need that MOSFET, could you please give more specific details about what to buy... https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=71-147-17&toc=19199??
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Montreal
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MOSFET linked above is o'k, 7A x 12 V = 84 W maximum control power, if you connect it directly to arduino.
 there is alternative:
http://www.sparkfun.com/products/10213
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Manchester (England England)
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@burgos
There is no resistor on that LED on pin 13. Pin 13 does not have an internal resistor, you are endangering your arduino.
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Helsingborg, Sweden
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Could this driver https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=73-296-26&toc=19777 be an alternative to the MOSFET? Any gains by doing that?
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Montreal
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No,
Quote
The UCD7231 high current driver is specifically designed for digitally-controlled,
point-of-load, synchronous buck switching power supplies.
It would complicated things far above your comprehension.
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Helsingborg, Sweden
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Ok  smiley-sweat

What kind of driver chip do I need between the Arduino and the MOSFET? Mentioned by Pito
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Manchester (England England)
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If you get a logic level FET then all you need is a 100R resistor to limit the current from the arduino pin. There is no need for a driver at these sorts of currents.

When you do need a driver there are lots available see:-
http://uk.farnell.com/jsp/search/results.jsp?N=0&Ns=P_PRICE_FARNELL_UK%7C0&Ntk=gensearch&Ntt=fet+driver&Ntx=mode+matchallpartial&suppressRedirect=true
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Helsingborg, Sweden
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The power FETs and resistors are now in place and it runs perfect. The LED-stripe is working just as it should. Thank you for all help.

For you who intend to use MOSFETs I can recommend this shield i found: http://www.robotshop.com/eu/productinfo.aspx?pc=RB-Spa-505&lang=en-US
I´ve ordered one of those for "integration" of the FETs to the Arduino.

I also bought a Cupperhead WiFi-Shield. Next step ahead.
 
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