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Drive LED


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?


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.


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



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


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.


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


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”


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