We are so sorry about that WIZ820IO datasheet didn’t describe the power consumption.
We will check the power consumption of WIZ820IO, and notify that to you as soon as possible.
If you want to need that quickly, refer to W5200 datasheet because WIZ820IO is based on W5200 chip.
The Maximum power comsumption of W5200 is 175mA when 3.3V and Temperature 25 degree.
So, You can roughly get the power consumption of WIZ820IO.
We think that the power may be enough to 200mA.
By the way, We are so so sorry again, We will notify the power of WIZ820IO to you ASSP.