Grblshield is using the TI drv8811 chips. They are way more powerful than they look. They can do 2.5 amps per winding and are happiest when running at 24 - 30 volts.
Run one at 2.5A then? How hot did it get? That device has about 0.6 ohm per switch so 2.5A dissipates around 7.5W,
which is about double the max dissipation for the chip according to the datasheet. Of course the switching strategy
affects dissipation as body-diodes may be carrying some of the current, but still I've yet to meet a single-chip chopper
drive chip that's upto multi-amp drive levels (DMOS fets don't go below 0.3 ohms or so, discrete FETs go down to milliohm
Typical bipolar steppers might have 1 ohm windings, so having two 0.6 ohm FETs driving it is wasting more that half
the power in the switches.
For 0.6A and 10 ohm windings, however, its a good match :)
Good catch, I copied those form Grblshield site, but I double checked the current which I doubt it as well.
Here is ti spec;
I guess ti use some additional cooling method than Grblshield does.
That is safe because the spec for IRFS3107 is 370 watts maximum power dissipation using a big heat sink.
It might need enough PCB area, if not available then d2pak heatsink.
further more we could use air cooling(fan), water cooling, ice-water cooling, peltiers, dry ice, liquid nitrogen, mini air conditioner, other type heat pump...
Electronics is art.
change ice cooling to ice-water cooling.
bottom line is;-
For 0.6A and 10 ohm windings, however, its a good match