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Topic: Pro Mini current (Read 1 time) previous topic - next topic

Robert Fisher

I see in the Pro Mini info that each pin can supply 40mA but what can the regulators on the board supply in total? I am going to have a ChronoDot, 3 leds and 2 - opto channels at 40mA each. Will the Pro Mini 3.3v handle this? Does anyone know of a low current optoisolator most of mine now are 50-80mA. I would love to find a lower current one that I could build a very low current package.


Robert Fisher

Never mind on the max current on the Pro Mini, I finally found it.

James C4S

I see in the Pro Mini info that each pin can supply 40mA

Yes the I/O Pins of the ATmega CAN supply 40mA but they shouldn't.  That is the max they are rated for and when run to max, will likey fail eventually.

Also, the VCC and GND pins can only handle a max total current of 200mA (same caution).  So turn on 4 pins at 40mA each and you're setting yourself up for future problems.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Robert Fisher

Hmmm, maybe I should see if I can reduce the current to around 20-30mA. I am using a NTE3086 in several of my Deumilanove's at 40mA Total current is output is about 143mA when everything is working. I guess I would also be better off using OKs with higher CTRs. The NTE is only 20% but 4n25s I think are 200-300% so that would be a better choice. Looks like a redesign time for some of them.

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