Arduino died after connecting to Laptop(A4988)

I have 2 A4988 drivers connected to arduino, also their VDDs and GNDs are connected to arduino. Everything was working quite fine if I was powering the arduino with 5V from laptop's USB. But now I thought to power the arduino with separate PSU of 11V along with 24v motor psu.

I connected the 11V PSU to RAW and GND of arduino
Removed all connections of laptop
When I powered both Power supplies(with same AC cable), arduino turned on.

but as I connected the entire board to laptop USB jack(Not the VCC, only GND, RX, TX and DTR), arduino turned off quickly and didn't came back on.


Why did this happen ? How should I fix this so it doesn't happen to next arduino.


Also here is the picture showing how all is connected, but only showing one driver.



PS : Laptop was on battery.

Hi,

You used a switch mode power supply? They are worse than usual 50Hz transformer supplies.

In general:
You need to protect ANY IO line that enters/leaves the board against overvoltage.

Or you need connectors with leading GND pins, to ensore that GND is the first signal to be connected.

Klaus

KlausST said:

Hi,

You used a switch mode power supply? They are worse than usual 50Hz transformer supplies.

Click to expand...

Yes, what should I use ?

Hi,

There are dedicated protection devices available.
Some are calle d "USB" protection diodes, but you may use them for other IO, too.

One is IP4220CZ6.

I recommend to add two resistors (maybe 100R each) before and after the protection diodes ...in sereies with the data lines

Klaus

KlausST said:

Hi,

There are dedicated protection devices available.
Some are calle d "USB" protection diodes, but you may use them for other IO, too.

One is IP4220CZ6.

I recommend to add two resistors (maybe 100R each) before and after the protection diodes ...in sereies with the data lines

Klaus

Click to expand...

But on which pins should I do that ? did TX line destroy it ?

Hi,

But on which pins should I do that ? did TX line destroy it ?

Click to expand...

How can I know which one of the pins destroyed the IC? I only have the informations you gave in this thread.

You need to protect ANY IO line that enters/leaves the board against overvoltage.

Click to expand...

To focus it: You need to protect ALL IO lines that enter/leave the board/case against ESD.

Klaus

... Or use optocouplers for all data lines.