L297 does not work in L297 L298 stepper driver

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
I built two L297 L298 bipolar stepper driver. I used one circuit some days ago (it was working) but today I tried to use it again. Surprising thing is that, it was not working, and after debugging, I found that L297 output lines ABCD were not working. I dont know why L297 is not working.

Then I connected SECOND similar circuit, I used it for some hours. After an hour break. I found, it was also not working in the same way like first circuit.

Any comment?
 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
Yes, it is similar to this as shown in attached image.

Here I keep Enable pin (l297) free. The circuit was working when it was free and when it stopped working then I connect it to +5v to keep it high. But there nothing happens.

Now it is not working. Do I need to reset L297 by making it Low then High again?
 

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bertus

Joined Apr 5, 2008
21,683
Hello,

At what voltage is Vref adjusted?
1 Volt will be the maximum value as that will sens a max of 2 Amps @ 0.5 Ohm sens resistors.

Bertus
 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
I tried adjusting the volt at Vref but all output lines ABCD keep low.

Both circuits are not working but there is not any burning sign or smock.
 

bertus

Joined Apr 5, 2008
21,683
Hello,

What voltages do you measure at Vref Sens1 and Sens2?
The outputs will be blocked when Sens1 or Sens2 is higher than Vref.

Bertus
 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
Recap: Two L297 L298 drivers was working but after a break of some times, they stopped working.

I checked the sense resistor volt with both circuits. The volt at both sense resistor with both circuits is 3.3V.
Then I set Vref volt equal to 3.3 or less with both circuits.
But still output ABCD lines with both circuits keep LOW.

Here I keep Enable pin (l297) free. The circuit was working when it was free and when it stopped working then I connect it to +5v to keep it high. But still it is not working (keep low).
Now it is not working. Do I need to reset L297 by making it Low then High again?
 

bertus

Joined Apr 5, 2008
21,683
Hello,

What is the value of the sens resistors?
When they are 0.5 Ohms as in the schematic, the current would be 6.6 Amps @ 3.3 Volts Vsens.
Then the L298 will be fried as the maximum allowed current is 2 Amps.

Bertus
 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
The volt at Vref is 3.3v. I try to reduce it to 1 or less.

I would like to show two bipolar drivers here, there is not anything to adjust.
Plz tell me if there is still something to take care of.


 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
In above two bipolar stepper driver circuits, there is not anything to adjust critically. I want to make me free from critical settings.

I want to drive my stepper motor (bigger one = 4kg) at 35-40v.
Please give your expert comments about above two simple drivers.

I think, my two L297 chips in two circuits have burnt out. In above two simple circuits, I think, there is no risk of component burning.
 

Thread Starter

crazybuoy

Joined Sep 19, 2010
77
I just want to use Mosfets instead of H-bridge chips such as L298, because it offers higher range of amp and volt. you may suggest any change in above circuits.
 

shortbus

Joined Sep 30, 2009
8,971
Why not use one of the many available dedicated stepper driver IC's? The L297/298 chips are very inefficient (drops more voltage) compared to a dedicated stepper driver.
 
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