Current sensing with TMC6300

Hi Folks,
I am trying to create a PCB with the TMC6300 motor driver IC and use current sensing. I am kinda new to this so forgive me if I overlook something.
I read through the data sheet of the IC and while it not states if its capable of LOW/HIGH or in line current sensing, looking at the block diagram it seems to me it’s the inline one. Now the problem is it uses a shared single point of measure point(chopper operation).

So the question is if I am right and I need the in-line current sensing method and if simplefoc supports this operation mode somehow(I read through the doc and it seems to me its not supported).

(ps.: this project is awesome, I spent already a lot of great time playing with an l298 and a smallish gimbal :slight_smile: )

@blase

Welcome to the forum. We hope you will find what you are looking for.

This driver has a little strange low side current sensing outputs. If you look carefully at the diagram, it has two power grounds, one for W and a combined U and V together. You have already discovered that but you don’t know what’s the implication.

This will create a problem for SimpleFOC because the low-side current sensing expects three or two independent low side signals, whereas you will feed W and U+V. In that case, since you need to attach sense resistors anyway and amplify the signal, I’d suggest you forget about low side current sensing and go for inline current sensing with a bidirectional current sensing opamp or a hall sensor. A lot more reliable and simpler.

SimpleFOC supports inline current sensing very well. However this driver is very low power and you will not really benefit much from adding current sensing to this chip. You may draw 1A max continuous and at most draw 2A peak for a very short time before you smoke the silicon. Of course if this is for educational purposes, by all means, go ahead and add current sensing.

Thank you for the awesome comment. Please let us know what else you may need.

Cheers,
Valentine

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Hi, and welcome @blase ,

For current sensing, we can work with 2 or 3 shunts, but not just one, and not with 2 phases combined on one shunt. So unfortunately I don’t think we support this driver for low-side sensing at the moment.

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Ohh you are right its indeed a low side one I see it now, thanks for pointing it out! I might play in the future with the current sensing but not for now then.

Welcome. Please post schematics and pictures of your PCB for others to learn, as well as your experience.

Cheers,
Valentine

Sure thing! Although I dont have anything to post yet, I hope I will be able soon.