The DVR8825 has 1.5 A/phase. The form factor is small (0.6" x 0.8").

However, for the required current, the chip overheats at 24 V. (I am told I need to design for 24 V supply.)

It seems anything around 4 A has a large form factor (e.g., DVR6575 is about 2" x 4"). They also cost significantly more, at least $90.

This paper and matching presentation seems to be evidence that internal-FET drivers exist at higher currents. Although, I did not see in either document what products they used. I found suitable driver chips with external-FETs (like the A4989). But I'd prefer to find at least one internal-FET driver chip.

Also, if you could explain how you found one I would greatly appreciate the knowledge.

 

The DVR8825 has 1.5 A/phase. The form factor is small (0.6" x 0.8").

However, for the required current, the chip overheats at 24 V. (I am told I need to design for 24 V supply.)

It seems anything around 4 A has a large form factor (e.g., DVR6575 is about 2" x 4"). They also cost significantly more, at least $90.

This paper and matching presentation seems to be evidence that internal-FET drivers exist at higher currents. Although, I did not see in either document what products they used. I found suitable driver chips with external-FETs (like the A4989). But I'd prefer to find at least one internal-FET driver chip.

Also, if you could explain how you found one I would greatly appreciate the knowledge.

I'd expect you to have a great deal of difficulty finding a chip to operate at those power levels.

 

The higher powered drivers will certainly be larger because it takes a lot more bulk to handle the much higher inductive spike energy from rapidly switching the motor windings off and on. And if you do get one be sure to add the external large capacitor that they recommend, to avoid destroying the module. The larger modules do require a big heat sink
I suggest checking with Automation Direct for higher powered stepper drivers. Also Oriental Motor.

 

The higher powered drivers

Do I even need a higher power driver? The application is basically a Nema 17 on a Nema 23 (or vise versa). The Nema 17 being used has the lower maximum rated current of 1.2 A: https://www.robotdigg.com/product/7/NEMA17-40mm-long-17hs3001-20b-Stepper-Motor

So I am debating going into designing a small form factor fitting A4989 PCB using the external FETs. On one hand, it seems Pololu's DVR8825 should work at 1.5 A/phase. But when texted on the breadboard, it overheats with a bunch of heat sinks on it after ten seconds.

 

I have also experienced stepper driver heating, but not recently. My solution was to not even consider those very small packages, which I am thinking are for much smaller steppers that are only powered for short times. The larger drivers cost quite a bit more because they are hybrids, while some of the smaller packages may be single integrated circuits.
Whatever you choose, be certain to read and understand all of the manufacturers application information, because there are some details that must be acmmodated, but they are not obvious.