Hey all,
I wrote a short, very simple guide to using PWM and a RGB LED,
Maple RGB Led Tutorial
I have a quick question, how much current can i source from each PWM pin?
Hey all,
I wrote a short, very simple guide to using PWM and a RGB LED,
Maple RGB Led Tutorial
I have a quick question, how much current can i source from each PWM pin?
The absolute maximum is 25 mA per pin or 150 mA total.
Your link doesn't work for me.
nully - It depends on what you are trying to do.
25mA is the absolute maximum from a pin.
If you look at the device data sheet at:
http://www.st.com/internet/mcu/product/164487.jsp
section 5.3.12 "I/O port characteristics" says:
"Output driving current
The GPIOs (general purpose input/outputs) can sink or source up to ±8 mA, and sink or source ±20 mA (with a relaxed VOL/VOH)."
I limit myself to 8mA in case I want to add other outputs, or someone else might use the circuit as a basis for something. At 25mA/output, two RGB LEDs would exceed the entire device current.
Ok, So the best way to do this is with 3 transistors, I'll revise my schematic then.
Ultimately I will be chaining RGB LEDs via several ws2801's but thats for another time.
I often just use a little mosfet - rated up to whatever current is needed - for LED's. But you can get arbitrarily sophisticated with feedback constant current drivers and such. Thanks for throwing the tutorial on the wiki!
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