A4988 vs DRV8825 Chinese Stepper Driver Boards
The Arduino Mega 2560 + RAMPS 1.4 combination is presently (December 2014) widely available and just as widely used to control 3D printers, either in the form of original components or more often than not, as inexpensive "Made in China" clones. Similarly, inexpensive "Pololu-style" stepper driver boards that plug directly onto RAMPS boards (usually four or five stepper driver boards are used) are available from China with two different stepper driver ICs, namely the Allegro A4988 and the Texas Instruments DRV8825.
How inexpensive can these stepper driver boards get? Well, right now a set of five Made in China A4988 stepper driver boards goes for around $6.50, whereas a similar set of five Made in China DRV8825 stepper driver boards is available for around $10.
This situation begs for the question: is it worth getting DRV8825 stepper driver boards instead of the more popular A4988 boards or not? Which one is the better choice for my 3D printer? Which one is more reliable / less unreliable? Can I mix A4988 boards with DRV8825 boards? This page is an attempt to provide sufficient information to make a rational choice and answer these and other related questions, if possible.
Contents
A4988 stepper driver board
I am pretty confident that the Allegro A4988 is an utterly tested and proven solution to drive stepper motors in RepRap printers, and this fact should not be ignored. As long as the following three conditions are met, they seem to be more or less bullet-proof:
- The stepper driver boards should not be inserted backwards in their respective slots on the controller.
- The stepper cables should not be disconnected from the boards while powered on.
- Proper airflow (i.e. active cooling a.k.a. a fan) should be provided.
Not the highest quality PCB and soldering I have ever seen, for sure, but... it works!
DRV8825 stepper driver board
And this is the new contender, a stepper driver board based on the Texas Instruments DRV8825:
Comparison table
The following table compares Made in China A4988 Stepper driver boards vs DRV8825 ones, for RepRap use:
| A4988 | DRV8825 | |
|---|---|---|
| Availability | very widely available | widely available |
| Approx. price | $6.50 / 5 pieces | $10 / 5 pieces |
| Max. theoretical current | 2A | 2.5A |
| Max. microsteps | 16 | 32 |
| PCB color | Green / Red | Purple |
| Stepper current adjust. trimpot | Yes | Yes |
| PCB layers | 2 | 4(?) |
| Small heatsink included | Almost always | Sometimes not |
| Active cooling required? | Recommended | Recommended |
| IC packaging | 5x5mm 28-lead QFN | 9.7x6.4mm 28HTSSOP |
Note that some important technical characteristics from the respective datasheets of the ICs are not directly comparable. For example, the DRV8825 is fully specified in terms of thermal characteristics, the A4988 is not. Another important characteristic that unfortunately is not directly comparable is RDSon, which is specified at different current levels in the respective IC datasheets.
Temperature Overload Protection
It is very important to keep the stepper driver ICs below a certain temperature during printing, since both ICs feature thermal overload protection that when triggered (typically when the die reaches a temperature of around 150~160 C), shuts down the output stages i.e. halts all commands to the affected stepper and in doing so, ruins the part being printed.
Heatsinks
It is not yet determined how much of a real impact the small aluminum heatsinks shown in the pictures above have on cooling the ICs, as both stepper driver ICs depend much more on proper PCB layout and solder pad contact (as well as proper airflow) for heat dissipation, rather than on dissipation through the top of the IC package. This is because both stepper driver ICs have an exposed metal pad under the chip that contacts the PCB and this is the "path of least resistance" for heat dissipation. The secondary path for heat dissipation is through the package leads and in this aspect the DRV8825 provides for possibly slightly better power dissipation compared to the leadless A4988. It is my understanding that dissipation through the top of the ICs is almost irrelevant here.
Datasheets
Use Cases
(add your own here)
| User | No. of Stepper Boards | Stepper Driver Type | Controller Board | Current per XYZ stepper | Current Extruder stepper | Time in Use | Picture if available | Notes
|
|---|---|---|---|---|---|---|---|---|
| AndrewBCN | 4 | A4988 | RAMPS 1.4 | 800mA | 1A | 3 months | N/A | Cooling provided by 80mm fan blowing directly over stepper drivers. Zero issues. |
| Template | ? | ? | ? | ? | ? | ? | N/A | (any extra useful information added here) |
