Hello,
I work with the stepper motor driver based on the A4983, but I realized that it can only operate with a motor voltage range between 8V-35V.
For my project, I need to command by microstep several 5V motors under 0.5 A.
So I wonder if the DRV8834 could be good for my application and what are the main differences with the A4983 stepper motor driver.
Thanks,
Regards.
Hello.
When using a current limiting stepper motor driver like these you can run the stepper motor at voltages higher than it is rated for. This can allow the stepper motor to achieve higher speeds. You can see more about this in the first FAQ on our stepper motor pages like this one.
You should be able to use that stepper motor with the A4983 stepper motor driver, and the A4983 carrier has a higher maximum voltage than the DRV8834, so it should be able to achieve faster speeds than the DRV8834 carrier.
On the other hand, the DRV8834 carrier has an additional microstep mode (1/32nd stepping) and an on board regulator, so you do not need a separate power supply for the logic side of the board.
Each stepper motor driver carrier has its benefits, but if you do not need the 1/32nd step mode, I do not see any reason you could not use the driver you have.
-Derrill
Hello Derrill,
First of all, thank you for your great reply.
I totally agree with you, and this is what I did.
Nevertheless, if I work with higher voltage than the motor is rated for ( according to the max current and the coil resistance), where the surplus of voltage is applicated? on the VDS of the transistors? If it is the case, the driver will heat up.
Regards.
I am not sure exactly what you are asking, but you can see more about how these stepper motor drivers do current limiting in the “Current Control” section of the DRV8834 datasheet. Also, note that these drivers will heat up in normal use, and that hot to you is not necessarily hot for electronics of this type.
-Derrill
Hello,
Ok I understand you, and I already see the “Current Control” section.
According the A4983 datasheet the current limit is done by: ITRipmax =Vref/(8RS)
Hence, in the pololu board, for Rs=0.05, we have current limit= Vref2.5.
Anyway, I just wonder when I work with higher voltage than Umax =ITRIPmax*Rcoil, all the voltage is apply on the motor, Or also on the VDS of the H-bridge?
And do you have an idea why my motor whistles?
Thank you for your replies.
Regards
Hello.
VMM is the voltage applied across the H-bridge. There are two MOSFETs that are on in series with each coil when the driver is powering the stepper motor, so the voltage seen by the motor might be slightly less. The “Functional Block Diagram” in the datasheet shows how the internal H-bridge is configured.
In general, stepper motors can be noisy. Could you tell me more about the whistle you hear? Is the motor behaving as expected despite the noise?
- Jeremy
Hello,
Yes, I’m aware of that.
My motor does what I want but the motion is not always smooth. This is a high-pitched whistle. I wonder if it’s because I work with higher voltage or a current slightly low than the current maximal. Indeed, The current starts to flow in the phases when I apply 6.4 V on VMM .
Regards
How did you set the current limit? How much lower do you have it set compared to the rated coil current of your stepper motor? Could you also tell us more about the stepper motor you are using (a link to its datasheet would be helpful)?
- Jeremy
