Mega328 - Maximum Current VCC -> GND = 200 mA
You are confusing a maximum safe current limit to the actual current consumption for the 328p chip which is more in the 25ma range when running at 5vdc @ 16Mhz, less if running at slower and at 3.3vdc. The rest of the current (up to 200ma) is what may or may be drawn from output pins wired to external components consuming the Vcc current.
Lefty