Is the Duet3 5 Mini+ able to support TMC2209 2A RMS ?
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I'm having a discussion with SKR users where they state they can use 2A RMS with the TMC2209s on their boards and that you can't with a Duet3 Mini 5+.
The documentation for the Duet3 Mini 5+ states: Up to 2.0A peak current (TBC)
The documentation for the Trinamic TMC2209 states: stepper motors up to 2.8A coil current (peak), 2A RMSPer the wiki documentation it seems that the Duet3 5 Mini+ DOES NOT support the 2A RMS that Trinamic states but it seems odd to be true.
Anyone able to clarify the issue?
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@jbarros
It's not the driver specs, but how much thermal energy can the Duet PCB sink, spread and convect, that limits the max current.
Just because some guy in Alaska can drive his steppers with 2A 24/7, doesn't mean it also works in Florida.
YMMV -
@jbarros 2A RMS is the theoretical limit of the TMC2209, unachievable in practice except for very short periods or using cooling methods that are not practical. It is unfortunately very common for power semiconductors to have current or power ratings that are way higher than can be achieved in practice.
Section 20.1 of the datasheet makes it clear that the 2.8A rating is possible for intermittent use only (1 second on and one second standby). It suggests 1.4A RMS as a design guideline.
However, the Duet 3 Mini provides a much greater heatsinking area than plug-in drivers do, so you can more easily keep the drivers cool, using a fan that blows cool air along the line of drivers on both sides of the PCB.
