What Does 4 mA Source/Sink Mean for AX0-AX7 I/O Pins When Reading 1.5V Battery?

Pin Description Min/Max
AX0 to AX7 I/O channels 0 V to 3.3 V, 4 mA source/sink


I want read the voltage on pin AX0 from a AAA battery, 1.5V. My question is: what does 4 mA source/sink mean? Can I use this pin for reading de battery's voltage?

Thanks in advance

Hi,

It is true that the difference between a source and a sink might be confusing in the beginning. Try to check the discussion here, see if this clears up things for you. Also check the discussions in the bottom of the page, they might be helpful as well.

http://digital.ni.com/public.nsf/allkb/A10122C63A7F5CFE86256B4C007491DD

I'm not sure but I think 0V and 3.3V may be the voltage range respectively for your pins. Source state is when your load is active, i.e. your load is connected to the source (thus the name source channel). 4 mA might be the rating when it is sourcing. Sinking is the opposite. Your load is connected directly to ground, sinking all current from the load. On what purpose do you seek by reading the battery's voltage?

Thanks for the replies both. I'm using it for an circuit were the a human body (only a part of the hand) needs to conduct the voltage from one point to another. So far I used a 3V3 3.3 V power output 100 mA for this, but the body's resistance so not low enough to conduct this properly. Voltage from a battery with +- 500mA on the other hand will do more than fine and I therefor thought instead of using the 3.3/100mA, why not use a battery and read the voltage off the battery instead. I just wasn't, and I'm afraid still, not sure what the 4mA source/sink means in this in this line. Somehow I can't seem to read the proper voltage on that pin. The voltage I read is a lot lower when comparig this with a regular voltmeter.