Improve standard Stepper driver with external Mosfets

[Wolfgang M. (wolfgam)]

Hello,

has anyone tried to improve standard ic stepper drivers with external 
mosfets?

For example:
Trimatic TMC2130 can drive up tp 2.5A peak. How to improve to 5A?

Trimatic has curcuits that can have external mosfets, but the are very 
expensive.

regards
Wolfgang

[Stefan F. (Gast)]

It is not so easy to add external transistor to such a standard product 
because the timing would not match.

There must be a certain delay between switching off one transistor and 
switching on the oppostive transistor (High/Low side), and that depends 
on the technical data of the transistors itself.

Also the chip internal overload protection cannot work with external 
transistors attached.

[K. S. (the_yrr)]

Wolfgang M. schrieb:
> has anyone tried to improve standard ic stepper drivers with external
> mosfets?
>
> For example:
> Trimatic TMC2130 can drive up tp 2.5A peak. How to improve to 5A?

since each output is a half bridge it could work, but Figure 1.2 in this 
[1] datasheet shows an arrow labeled ISENSE from each halfbridge, 
aditionally to the current sense from the Resistor. So i would expect at 
least some (if not all) functions related to current sensing to stop 
working properly, which is basically everything. the Datasheet says 
something about an integrated current sense option, so maybe these can 
be disabled.

additional dead time needed for external Mosfets might be a problem 
(that has no easy solution). SOA control (for the mosfet) is not 
possible anymore.
each output ranges from 0V to VCC, external mosfets would only take up 
to 20V  between gate and source, so there would need to be (a very fast, 
at least some orders of magnitude faster than internal switching) 
circuit to keep the gate voltage in the allowed range. the more delay 
until the external mosfet switches, the more malfunction is to be 
expected.

there are many Motor Drivers that can handle 46V and 5A, why don't you 
take one of those?

[1] 
https://www.trinamic.com/fileadmin/assets/Products/ICs_Documents/TMC2130_datasheet.pdf

[Schorsch X. (bastelschorsch)]

Use TMC5160, which can drive external Fets up to sevaral Amps directly. 
Coupled with dual N-Channel Fets gives you a nice little board. Or use 
the TMC5160 BOB (Break Out Board) and change the fets on this module to 
your needs.