I need some technical advise on if I should stay with the L6470 (HTSSOP) or move to the L6480. Both are stepper motor drivers from ST.
The difference being that the 80 is designed to drive external MOSFETS. They cost the same and operate with a similar command set. The reason for the change is that, it seems impossible for the 70 to drive stepper motors with low phase resistances (e.g. 2Ωs). To get my current stable of 70s to drive such low resistance motors I have to add a power resistor to increase the impedance (e.g. 5Ωs). This generates a lot of heat. I’ve measured the resistors going up to 98°C running off 12V. The external MOSFETs of the 80 shouldn’t get that hot during operation, and even if it did, I can always add heat sinks or put the MOSFETS on the bottom of the PCB so that they are thermally coupled to the Aluminium mounting plate.
By having a higher current capacity, I could drive any motor I wanted to; costs aside. This would give more flexibility in terms of choosing motors. No longer will I have to worry about availability or cost. I could put anything in and calibrate accordingly.
Lastly, I could move to the L6470 Power SO Package (like GHI used to make) as this would keep the costs the same and reduce the PCB rework, however the power handling won’t be as good as the 80.