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Topic: ULN2803A continuous current (Read 1 time) previous topic - next topic

afremont

That's why I said they would be mutually exclusive.  At that dissipation, the part will be no where near 25C.  Just adding some levity.

I know you didn't say 25mA, but much documentation does.  Even the OP was ready to run them at 20mA.  It's just not necessary was my only point on that.
Experience, it's what you get when you were expecting something else.

Shpaget

Thanks guys.
I see I will need to give this some thought and list all the LEDs I intend to hook up on one chip and pick the voltage that will be most suitable for majority of outputs.
Since I'll have multiple of these independent devices I can set each at different voltage.

dc42

Why not use TPIC6B595 instead? That way you'll save on output pins as well (it's a shift register). It has lower voltage drop than the ULN2803A, and you can sink about 100mA per output from all 8 outputs continuously, without it overheating.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

Shpaget

This sounds promising.
I found this library and so far it works quite well for me and my 74hc595.
http://bildr.org/2011/08/74hc595-breakout-arduino/

Do you think it might work with TPIC6B595 as well?

dc42

I don't know that library, however the 74HC595 and TPIC6B595 are driven in similar ways, so it will probably either work as-is or with minor modifications.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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