Hi everyone,

I would like to use this Demultiplexer : HEF4514B with my arduino mega :

I would like to know if it's possible to use my Demux on this card with these connections :


Vdd => 5V /E => GND A3, A2, A1, A0 => DIGITAL OUTPUT of arduino O 0 to O15 => 1 LED by pin ( on a plate ) VSS => GND EL => DIGITAL OUTPUT of arduino

Thanks for your help !


Maybe. The data sheet i found for your demux chip does not seem to say what current limits are for the outputs. It possible it might only light a led to a portion of its maximum brightness. But you should still use a series resistor anyway. You would need only one series resistor, because only one of the demux outputs will be high and only one led will be on at any time.

My question is, with all those outputs available on your Mega, what do you need the demux for?


Or more to the point - why do you want to use an obsolete HEF4514B for a completely inappropriate purpose?

OK, the proper version if you must do this is the 74HC4514 and it specifies an absolute maximum of 25 mA so you need to use 180 Ohm series resistors with the LEDs.

What you should be using however, is a pair of TPIC6B595s (just three Arduino pins controls both or indeed a dozen of them in cascade). Note these only pull outputs down but can drive 150 mA per output and switch about 50 V. You always need the current limiting resistors for LEDs.