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Topic: Will this driver drive this stepper? (Read 319 times) previous topic - next topic

andypop

Hi thanks in advance for your help! Decent programmer but very new to the hardware side.

My question is hopefully cut and dry:

Can this stepper motor be driven by driver?


My intention is to use a tinyG (which uses those drivers) to drive two of those steppers but I'm not very clear on whether the current is sufficient - the motor shows a vague "1.9A" current rating -is that comparable to the RMS current on the driver?

jremington

#1
Jan 16, 2018, 09:42 pm Last Edit: Jan 16, 2018, 09:45 pm by jremington
For a step motor, the current rating is the maximum steady state current per winding, stated to be 1.9 A.

So yes, a stepper driver that claims 2.5 A per winding should work, except that driver manufacturers tend to be very optimistic, and may expect you to provide forced air cooling, heat sinks, etc.

Case in point: the sellers of the ancient L298 chip all claim 2A per winding, but in practise most people never get more than about 1 A.

Robin2

The TI datasheet says the RMS current is 1.75 amps and this line from Section 10.1.1 of the datasheet seems to me to sound a warning
Quote
In general, the more copper area that can be provided, the more power can be dissipated.
...R
Two or three hours spent thinking and reading documentation solves most programming problems.

andypop

Thanks for the replies!

For what its worth cooling via heat sinks/a fan is doable for this project.

My main concern is as Robin2 stated - the RMS Current for the driver says 1.75A, peak 2.5A and I'm not entirely sure which value is most relevant to the motor's stated 1.9A.

I'll be running two of these from the board - is it reasonable to assume if the board is well cooled this is OK?

jremington

#4
Jan 17, 2018, 04:49 am Last Edit: Jan 17, 2018, 04:52 am by jremington
Do you have the skills to design a board with excellent heat sink capabilities?

I would go with the stated rms current value.

You do not have to run the motor at its full rated current, unless you are desperate for the maximum possible torque, in which case your mechanical design is questionable.

Robin2

You do not have to run the motor at its full rated current, unless you are desperate for the maximum possible torque, in which case your mechanical design is questionable.
On the other hand a stepper motor should be operated with sufficient excess torque available so that there is no risk of missing steps.

In view of the OP's uncertainty my suggestion would be to buy a ready-made stepper driver that can supply at least 4 amps - to give some headroom.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

#6
Jan 17, 2018, 12:53 pm Last Edit: Jan 17, 2018, 12:54 pm by MarkT
Stepper motor currents are peak values, ie the current amplitude of each phase, and the phases are
driven in quadrature in microstepping.  Don't use rms with steppers, it will confuse you...
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

MarkT

So yes, a stepper driver that claims 2.5 A per winding should work, except that driver manufacturers tend to be very optimistic, and may expect you to provide forced air cooling, heat sinks, etc.
We say 2.5 marketing amps, ie 1.5 real amps!
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

andypop

Seems like the consensus is "maybe but probably not"! I guess I'll check out a higher amp driver or lower current motor. Thank you for all the help everyone!


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