What the maximum mA for mega

Other Hardware General Electronics
1

Hi,
I have a switching adapter, output details : 12V 1000mA,
It is ok to connect my arduino mega to this adapter?

2

Yes.
The current capability of the power supply doesn’t matter the Arduino will only draw as much current as it needs.
While 12V will work the regulator on the Arduino will get hotter than it would if you could use a lower voltage.

3

RefaelGanesh:
I have a switching adapter, output details : 12V 1000mA,
It is ok to connect my arduino mega to this adapter?

Yes, as long as you don't draw a lot from the 5volt pin, the 3.3volt pin, or the output pins.
Total current draw from the Mega (for sensors, shields, etc), is limited to about 150mA with 12volt on the DC socket.
Draw more than that, and the regulator will overheat and shuts down (if you're lucky).
If you need more than ~150mA, then use a lower power supply voltage.
Or power the Mega with a 5volt phone charger on the USB socket.
Leo..