Bi Polar stepper driver with L298N

Hello,
I'm trying to drive the 17HDB002N Stepper motor using the L298n full bridge chip.
each phase wire is rated at 1.6 ohm and can be driven by 12v or 24v at a rate of 2A or 1.5A respectively.
my problem is that when I connect it everything runs for 5-6 turns with no problem, but then the chip gets extremely hot and the motor doesn't work smoothly.
Further more I'm using a 12v 5A transformer to drive but it seems that once the chip heats up the transformer doesn't withstand the current consumption and the voltage drops.
What am I missing? if I connect a 12V/1.6ohm=7.5A even though the specs state 2A.
Do I need a current limited source? Do I have to add something to the code in order to prevent this from happening? (I'm using the stepper one revolution example)
Thank you

Its a low impedance stepper motor, an ohm or two only, not suitable for driving this way.

You need a current-controlling driver (this is the normal mode for steppers), such as a DRV8825
module.

You may have damaged your L298N through over-current, and possible overheated the motor
windings too.

A motor suitable for running at constant 12V will have a winding impedance of 40 ohms or so,
but note that constant voltage drive for a stepper severly limits the top speed (150rpm to 200rpm
typically). Constant current drive does not limit it in this way.

These links may be of interest
Stepper Motor Basics
Simple Stepper Code

...R