What's in the TMC5272 EVAL kit?

cstanton said:

Depending on which connector is used can take up to 20v or 28v

I think you're misunderstanding what the connectors are for.

+VM is the motor supply, +VL is an input that goes to a regulator on the other board that looks like it provides the logic supplies in the absence of the USB supply (I haven't investigated the processor board at all). You always need a motor supply or the motor won't do anything. +VM is limited to 20V because that's the limit of the h-bridges in this particular stepper chip (look at its datasheet for that one). If you only have power on the +VM input, the +VL rail gets its power from the +VM supply via a schottky diode (so you'll see the +VM voltage less about 0.3V on the +VL connector).

The +VL connector (8-28V) is there only for the situation where you want to operate a motor with a very low supply voltage. If +VM is less than 8V, there then won't be enough voltage for the regulator, so you can also apply a higher voltage to the +VL input to operate the regulator. That's safe because the diode will then be reverse biased and isolate the two power connectors.

One thing you mustn't do is actively drive the +VL input with a voltage lower than that driving the +VM input or you may risk damaging the diode or your PSUs, so where you do use both connectors you'll need to apply the supplies in the right order.

I think the overall rationale for this is to ensure that there's always power on the logic supplies to the stepper chip whilst there's motor power present, irrespective of what's being done with the USB. Heed the warnings about connecting everything together before applying power, and, if you want to substitute your own processor board for theirs, you'll probably need to contrive something similar to what they've done to maintain the logic supply to the stepper chip.

Although this seems a little confusing, to be fair to ADI this is an evaluation board aimed at design engineers intending to design products with the stepper chip: they weren't trying to design a plug-and-go motor controller.

This is my own understanding, based on a quick flick through the manual and looking at the schematic. It's intended to be helpful, but anyone looking to use the board should investigate further and satisfy themselves from the documents provided by ADI.

jc2048 said:

I think you're misunderstanding what the connectors are for.

jc2048 said:

Although this seems a little confusing

Indeed, in some cases like this one, I can only pass on the information I am given. There has been a lot of confusing information provided to us about this kit and having these forum posts where it can be discussed hopefully reduces that confusion for those involved in the competition.  Thank you for contributing.

jc2048 said:

I think you're misunderstanding what the connectors are for.

jc2048 said:

Although this seems a little confusing

Indeed, in some cases like this one, I can only pass on the information I am given. There has been a lot of confusing information provided to us about this kit and having these forum posts where it can be discussed hopefully reduces that confusion for those involved in the competition.  Thank you for contributing.