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Drive LED


#1

Hi, I’m wondering if it is OK to drive an LED directly from the Domino (Di2, Di3 etc.). Or, is it necessary to use a driver circuit that can supply more current? How much current can the pins supply?


#2

You can drive standard LEDs with no problems at all. Only high current leds are not such a good idea.

Note: always add a resistor.


#3

So, driving an LED @ 20ma is not a problem? What is the max current that can be supplied by the chip without damage?

Thanks


#4

I think the rating is 4mA but going to 20mA will work (voltage will not be withing specification though)

Do not use anything more than 20mA


#5

If you are running more then 20mA you could use a trisistor for switching it with fez. This was the current will not flow through fez.


#6

Gus !
I thought the current on the pin was 8mA… Is this a failsafe? " When multiple LEDs used on a single port blah de blah "

Cheers Ian


#7

You can check the LPC23xx datasheet for more accurate number. In general, you shouldn’t connect more than an LED to a pin on a microcontroller. The pins are to drive “signals” not “loads”


#8

Yes, that’s why you can control loads with either relays or transistors. (or similar)