Hello, i supply power to my Arduino Ethernet using an Ac-Dc adapter (wall wart) 9V - 1A via power jack, therefore I can supply voltage (9V) using Vin pin but about current? Is there any limitation (40mA) or i can access through this pin to the maximum current of the adapter? (1A). Thanks everyone will answer!
The VIN pin connects direct to the voltage regulator.
The regulator is rated (IIRC) at something like 800mA, so you can't draw more than that through the regulator without it melting.
The header connectors are typically rated at 1A, though that may vary depending on manufacturer.
So yes, you can, pretty much.
Thanks Majenko. So i cant draw much more than 800mA from the Vin pin even if the adapter could supply 1A?!
You can draw up to 1A, but only an absolute maximum of 800mA of that can be used at 5V - actually considerably less because it will get too hot due to insufficient heatsinking.
....So even if i supply Voltage using the power jack i can access through the Vin pin to a regolated Voltage of 5V (none 9v as i supposed)...in this case the Vin pin specifics are the same of the 5V power pin (output regulated)..? Right?
Reading the board specifics I figured the Vin pin and the powe Jack connected before of the voltage regulator, the others output pin (5V and 3.3V), instead, after the voltage regulator. So I supposed the header maximum current limitation (more than 1A) for the Vin pin and the regulator maximum current limitations for 5V and 3.3v outputs!...
I thought the Vin pin and the positive pole of the power Jack internally connected...
....any ideas?! Vin pin and the positive pole of power jack are the same (internal connected))? ....is it correct?
I know there's a diode in the mix somewhere, but I can't be fagged to dig out the schematics right now, but diodes aside, both the barrel jack AND the Vin pin connect to the INPUT of the 5V regulator. So what you put in to the barrel jack you get out of the Vin pin, and (possibly, diode permitting) vice versa.
Ok I read (again) the board specifics but I didn't found anything about current limitation for Vin pin. I agree with you : "what I put in the power Jack I get in the Vin pin". I think there's no diode because:
VIN. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin.
!
There is a diode between the barrel jack and the rest of the circuitry (including Vin). So, what you put in to the barrel jack you get out of Vin minus a few hundred mV (diode drop). BUT, what you put in to Vin does NOT come out of the barrel jack.
The current limit of the Vin is purely down to the connector they used and the width of the copper traces on the PCB.
Here's a typical elcheapo header connector: http://www.rapidonline.com/Cables-Connectors/Single-Row-PCB-Sockets-2-54mm-Pitch-180585 - apparently the manufacturer rates it at 3A, so well in excess of your 1A. The traces look about 1mm in width, so that should be able to cope with about 2.5A with only a 10°C temperature rise over a distance of 1", so that is well in excess of your 1A too.
Thank you very much, Majenko! 8) 