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Blowing up a lot of A4988, Arduino, Plz Help


#1

Hi there,

i am now actually very frustrated. I already damaged 3 “A4988 Stepper Motor Driver Carrier with Voltage Regulators” and i dont know why this is happening.

When the Driver is damaged the 5V Supply on the board gets very hot, if i dont remove the main supply the main chip explodes in the upper right corner. I think the cause for this is an overvoltage applied on the board which first damages the chip and after that there flows a high current from the 5V supply in the chip and burns it.

My configuration is the exactly how it is mentioned in the description on the web page. The only difference is, that i also use the 5V from the board to power my microcontroller. On the Powersupply Port is an 2000uF Capacitor.

So there are the following components:

Notebook -> programing the arduino (stays connected)
Arduino -> GND and VCC connected to the pololu board
pololu board -> connected to power source (24V)
power source -> i got two types, a lab power supply and a meanwell rail power supply
stepper motor connected

I think it destroys the chip when i disconnect and reconnect the the powercable. I do this for testing my programs etc… the rail power supply seams to be more likely to damage the chip

What could i do to secure the chip? I cant figure out whats the cause for the problem… maybe a voltage peak between the laptop and the powersupply and the 5V powersupply.

I dont have enough chips to destroy to figure out what makes this damage. Could you plz help me how to secure the chip at all costs? Maybe supressingdiodes 28V and 5,8V on the Chip pins?


Smoked 8825
#2

Hi.

I am sorry you are having problems with your A4988 stepper motor drivers. What are the current and voltage ratings for the stepper motor you are using with the drivers? Did you adjust the potentiometer appropriately to set the current limit before driving the stepper motor? Could you post pictures of your setup that clearly show all of your connections?

- Jeremy


#3

Hi,

i added a picture of my connections. The motor is not a problem. I decreased the current to such a low level, that the A4988 chip doesnt get hot. Even if i let it stay connected for a long time ( for hours…). In general the configuration works fine. Motor runs good, nothing gets hot. The point when it crashed is, when i connect/reconnect different power sources (the 24V ones).

The Usb-notebook-supply is only connected to program the microcontroller. The microcontroller decides for it self where it gets the power from. I m now thinking it is a problem between the 5V regulator and the notebook supply. Some threads before, there was another person with a similar configuration and the problems.

I think i m gonna buy suppressing diodes and put them arround the 5V and 24V pins of the driver to prevent any kind of overvoltage.



#4

I notice that in your diagram, the motor and notebook supply are not connected together externally.

There is a significant possibility of a “ground loop” due to the notebook and the 24V power supply being connected to different branches of the AC mains, which can lead to significant voltage differences and currents between the notebook and power supply ground connections. Check for this by disconnecting the motor power supply (both power and ground). Then power everything up and use a multimeter on the AC voltage setting to determine whether an AC voltage exists between the notebook USB ground and motor power supply ground.

If this is the case, after programming you could power the arduino from a regulator that steps down the 24V motor power supply to something more useful.

Also, USB power can be very noisy and should be suspected if intermittent problems arise.


#5

Even though you have an extra capacitor connected, it sounds like you might be damaging your boards with LC voltage spikes. Could you verify the 2000uF capacitor is connected correctly? What voltage is the capacitor rated for? Could you post photos of the physical setup?

By the way, if you have the regulated 5V output from the driver connected to VDD, you should remove the connection from USB-notebook-supply to VDD.

- Jeremy


#6

hey Jim,
that might be the reason. I tink i’m sitting in front of two seperated ac mains. The notbook is connected in a separeted one than the powersource. Its so built up in our labratory. When i measure the ground between the powersouce and the board power ground, i get up to around 7V AC-Voltage. When i disconnect the power from the notebook this Voltage disaccours. Could this be enough to damage the board? I dont really get the background behind that :angry: You have an idea how to prevent that, ok i dont connect that type of connection again, but when someonelse does that :smiley:

jeremy: dont think that the capacitor is the problem. directly connected to the board (about 5mm). Rated for up to 50V (eletrolytic, correctly poled)


#7

The 7VAC between the grounds is almost certainly the problem. The peak voltage difference is sqrt(2)*7 = 10 volts, easily enough to destroy logic circuitry. If you plug the laptop and power supply into the same AC branch (use a multiple-outlet power strip if you need to) the problem should go away.

There are many reasons why this can problem can occur, so other than the above, I can’t say what else to do to prevent it.