THE Bipolar Stepper Driver. Have you seen it?

[irving2008]

... I don't understand what your talking about with the JEDEC standards.

Thats exactly my point... the TISSOP package heatsinking needs are very critical and the 28degC/W thermal rating is measured under strict conditions, one being the area of copper ground plane used as a heatsink and the number of vias that act as heatpipes from the contact pad to the ground plane. By shrinking the board size you've compromised your heatsink performance dramatically.

I looked at the A3979 and I finally chose the A3977 simply because it stopped at 1/8th step as I feel like 1/16th step is way overkill. As you would need a machine that was very precisely made for it to be worth it.

Disagree, depends on desired resolution and screws used, nothing (directly) to do with how well machine constructed.

I however didn't check out the Rds on...that does make its mosfets more efficient I'll have to think about that one.

Rds is your enemy, minimising it is always a good strategy, Esp on the brushless motor controller I'm designing at the mo for 250A continuous, 300A peak! The MOSFETs for that are 0.02ohm and I'll still need 10 or more per channel if the heatsink is going to be
smaller than a football pitch