100 milliamp coil current...transistor or MOSFET?

Using Arduino General Electronics
22

The notes clearly describe 300mA of current among the IO pins, so yes I'd say each of the Vcc pins can handle 200mA for 400mA total consumption.

There is nothing that describes an absolute max package rating.
The 32 pin packages have a 3rd set of VCC/GND pins even.

If you look at the '2560 datasheet, the Absolute Max is shown the same way:

DC Current VCC and GND Pins................................ 200.0 mA

yet the notes describe even more current, 800mA, so clearly the Per Pin current is being described in support of the 5 pairs of Vcc/Gnd pins. Current Per Package would be dependent on Operating Temperature, clock frequency being used, both of which have an impact on internal temperature, along with IO current being controlled.

Notes:

  1. "Max" means the highest value where the pin is guaranteed to be read as low.
  2. "Min" means the lowest value where the pin is guaranteed to be read as high.
  3. Although each I/O port can sink more than the test conditions (20mA at VCC = 5V, 10mA at VCC = 3V) under steady state
    conditions (non-transient), the following must be observed:

ATmega640/1280/2560:
1.)The sum of all IOL, for ports J0-J7, A0-A7, G2 should not exceed 200 mA.
2.)The sum of all IOL, for ports C0-C7, G0-G1, D0-D7, L0-L7 should not exceed 200 mA.
3.)The sum of all IOL, for ports G3-G4, B0-B7, H0-B7 should not exceed 200 mA.
4.)The sum of all IOL, for ports E0-E7, G5 should not exceed 100 mA.
5.)The sum of all IOL, for ports F0-F7, K0-K7 should not exceed 100 mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test condition.
4. Although each I/O port can source more than the test conditions (20mA at VCC = 5V, 10mA at VCC = 3V) under steady
state conditions (non-transient), the following must be observed:

ATmega640/1280/2560:
1)The sum of all IOH, for ports J0-J7, G2, A0-A7 should not exceed 200 mA.
2)The sum of all IOH, for ports C0-C7, G0-G1, D0-D7, L0-L7 should not exceed 200 mA.
3)The sum of all IOH, for ports G3-G4, B0-B7, H0-H7 should not exceed 200 mA.
4)The sum of all IOH, for ports E0-E7, G5 should not exceed 100 mA.
5)The sum of all IOH, for ports F0-F7, K0-K7 should not exceed 100 mA.
If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current
greater than the listed test condition.
5. Values with “PRR1 – Power Reduction Register 1” enabled (0xFF).