Driver limitations

[WilliamD]

This question will more than likely only reveal more that I don't know what I'm getting into. I'm getting the 276oz motors off automation direct, and a powersuplly that will do 40v at 8 amps. Way more power than my driver board (xylotex) will be able to handle. But I want to get the setup so that I can make my own driver board, like the one on Pmino's site. What is it that limits the boards like the HobbyCNC and Xylotex boards to just safely running 24v for the motors? I notice that the boards you build yourself can handle more than the standard 3 amps also. I'm probably asking too much with this questions. But can you simply modify Pmino's board to run safer at higher voltages? What's the limiting factor? Thanks in advance!

[ger21]

The chip that does most of the work in a Xylotex can only tolerate 35V max before it fries. To use it safely, it should never see more than 30V.

[pminmo]

Ger21 is correct, the 3977 chip can't run at higher voltages. It will fail. WilliamD, are you ok with full step and half step only?

[WilliamD]

Yeah, I really don't need a lot of the microstepping. The resolution for my needs really isn't that great. I figured it was basically the processor of IC that was the limiting factor. When you make your own, can you just get one that handles more voltage? Or is this a scenario where you have to go about it a totally different way and it gets expensive? I was looking on your site again and noticed there are boards that do 45v, but they are "modular" boards. I don't have to have it all on one board. What makes these capable of that. Sorry for all the questions. It looks like I'll be building those boards shortly after getting the CNC together. Thanks for your quick replies!

[ger21]

Originally Posted by WilliamD Yeah, I really don't need a lot of the microstepping. The resolution for my needs really isn't that great. I figured it was basically the processor of IC that was the limiting factor. When you make your own, can you just get one that handles more voltage?

If there was an avilable IC that handled higher voltages, everyone would be using them. Unfortunately, I don't think there is.

Microstepping is more important for reducing resonance in the motors than resolution. Using half or full stepping can cause resonance which can lead to lost steps. It depends on the application, though. It may work fine for what you want to do.

You also might want to check out the bare boards from www.embeddedtronics.com 3A and 55V, although they recommend 44V max.