I wanted to push my TMC2209 driver design to high-er current. The driver chip is relatively small and even at moderate 1.3A RMS motor current it gets very hot very fast.
Now to be fair 1.3A RMS is probably more than enough to drive most NEMA17 stepper motors. However every once in a while one can get a 1.6A motor or in my case a 1.7A motor. Now in most cases it is not required that you drive the motor with it’s maximum rated current, I just wanted to push the driver and see how it fairs under load.
Here is a picture of my very messy desk with the test setup:
I have my 1.7A NEMA17 motor on a linear rail I used for the test. Above it you can spot my Seek Compact Pro thermal camera. It is not the most accurate instrument, but does the job +/- 5 degree C.
The driver board has one 14x14x7mm heat sink on the driver chip and one 25x25x5mm heat sink on the back of the board, There is also a low RPM 5V 40mm fan blowing air horizontally across the driver boards.
First I configured the driver to use 1.6A RMS current and run a series to G1 X100;G1 X0 commands to move the axis back and forth. I used relatively slow speed, because from my experience this heats the driver the most. This test was uneventful (aka no smoke or major errors), so I proceeded to configure the driver to use 1.7A RMS current.
Here is a picture of the temperature of the board after about 15 minutes of moving the axis back & forth:
The hottest spot is around 54C. While the colors are very dramatic, this is quite cool for this type of setup.
The back side was about 45C:
In conclusion the test was very successful. In previous experiments the drivers would heat up to 70C. In this setup 54C was quite reasonable for the amount of current the driver was handling.