A4988 building up oscillations while holding

This will take a bit to load if you watch it in-browser.

When plugged in and being driven by an Arduino with any program loaded on it, (the loaded program in this video is empty) the motor initially holds just fine. After ~20 seconds, the stepper starts “ticking,” which is very quiet in the video, but audible. The ticking grows more rapid, and when ticking, the stepper’s hold is very easily broken. Once it’s ticking, unplugging and re-plugging in the system causes a brief lapse in ticking, but it starts right up again quickly.

Any idea what’s going on?


It sounds like your driver is probably overheating, at which point its thermal protection is causing it to shut down. What do you have your current limit set to? What is the current rating for your stepper motor (it seems pretty beefy). Some people add heat sinks to our drivers so that they can deliver more current before overheating; have you added a heat sink?

- Ben

I have the current limit set to 1.75A, which is the rating of the motor, and I do have a heatsink. I just checked, and the heatsink does get quite hot. What do you reccomend for a heatsink, mine is quite small. I could also add a fan.

We have not really characterized how heat sinks affect our A4988 carriers, so I don’t have much specific advice to offer you. However, generally speaking, it is not easy to get 1.75 A per channel out of the board. A larger heat sink and fan should probably help.

I know a lot of people have been trying to push these drivers to their limits in various applications, so you might find some good suggestions if you google around. Here’s one example:

arduinodabbler.wordpress.com/201 … er-driver/

You also might find some information if you search our forum for something like “A4988 heat sink”.

- Ben

Loike (I guess) everyone else using this board, I’ve had issues with overheating.

Kudos for bringing out the ‘black edition’.

My suggestion for further improvement would be to offer a version with heat-sinks fitted (or at least offered in the kit).
AFAIK the best suited is Enzotech MOS-C1 Copper http://www.enzotechnology.com/mos-c1.htm, with a 6.35x6.35 footprint.
This board is ‘nice and tiny’, but the downside is that makes it next to impossible to fit a decent sized heat sink, especially since the tiny driver chip is surrounded by taller components, and its top surface doesn’t even safely clear and header pins that will typically be soldered on.

I’m happy to characterise this for you if you want…once I get my hands on some of these heatsinks.
Given the tiny area and tiny thermal inertia of the A4988 itself, these must make a huge improvement in current capability, even without a fan.


Thank you for your feedback. I would be very interested to hear about your results if you try out our A4988 carriers with those heat sinks.

- Ben