Arduino Forum

General Category => General Discussion => Topic started by: RCFisher on May 03, 2011, 09:38 pm

Title: Pro Mini current
Post by: RCFisher on May 03, 2011, 09:38 pm
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.

Thanks
Title: Re: Pro Mini current
Post by: RCFisher on May 03, 2011, 10:07 pm
Never mind on the max current on the Pro Mini, I finally found it.
Title: Re: Pro Mini current
Post by: cmiyc on May 04, 2011, 07:15 pm
Quote
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.
Title: Re: Pro Mini current
Post by: RCFisher on May 04, 2011, 07:36 pm
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.