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Topic: PWM 3V 200mA High Power Led from 3v soure (Read 1 time) previous topic - next topic

mjkzz

Sorry, read the wrong data sheet ... but take a look at MOSFET FDS6690A datasheet, Fig 1 and Fig 2. It is a SOIC 8 package, however.
Search for "mjkzz" on eBay :-)

cio74

FDS6690A looks fine at 3V, I have to do some research in here, thanks for the tip.

Grumpy_Mike

Quote
Any example that I can use as a startup point, on that web page all is pure theory.

Now you have me puzzled. I don't know what you consider pure theory but that site is exactly the opposite.
As a start you can take the last diagram on this page:-
http://www.pcbheaven.com/userpages/LED_driving_and_controlling_methods/index.php?topic=worklog&p=5
and from the collector of that transistor connect it through a 1K resistor to a PWM output of your arduino.

cio74

Mike, the trouble I have is due the formula:

VM = VDD - Vf_LED - 0.7

now, Vdd=3v, vf_led=2.5v

VM=3 - 2.5 - 0.7 = -0.2v

How this would ever work? This is the reason I have asked in first place if it's possible at all. I think I'm missing something in here?


Grumpy_Mike

Sorry but where is that formular from and what is VM?

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