TMC2100 How hot?

Chris Vaughan

I've put together the v1.27 miniPCB with TMC 2100s. I've got CFG1/2/3 at GND/open/open for 16 microstep spreadCycle mode. I'm using polulo 1209 stepper motors (2.7V 1A). Just waiting on some pulleys to put it on an EQ5. All is working well, connecting via bluetooth with the android APP and skysafari.

My question is, how hot should the TMC2100s get ?
They are getting very hot after 10-15min. So hot that I can't touch the heatsink on the TMC2100s for more than a few secs. This was with Vref set to 1V (which I'm sure is what a 1A stepper should be set to on the TMC2100). I dropped Vref to 0.7V and its still hot. This was with it running on a 12V supply, but just got a 12-24V converter and its still hot (with Vref at 0.7 - 1V). The stepper motors get warm but not hot. If I drop Vref too much (e.g. down to 0.5V) then it stalls at any GOTO speed above 1deg/sec.

Is this how it is? Mind you, ambient temp was about 28C at night when I tested it. Sydney was the hottest place on the planet yesterday!!

Cheers Chris

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