[SOLVED] Current controlling issue in L298

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Ranbeer Singh

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Hi guys,

I am getting a issue in L298 circuit. I know if load increase on motor then RPM reduces & current increases. But i want to control it. I tested my circuit and found that...

free running current is 0.35A
Load current is 0.76A
Jam pulley 1.7A.

How can i control it. I mean that free = 0.35A, load = 0.76A & jam = 0.76A.

circuit diagram



Please help
 

You should short seance resistor to ground (Pins 1and 15). It will decide the maximum current flow to the motor. Here the seance voltage is 2V max(practically 1.5 V to 2 V). So you should calculate the resistance 1.5V/0.76A = 1.97 Ohms 1W or more
 
Thanks your valuable reply

I think it will work, but i am unable to understand that you are saying 1.97E or more.
What's formula of calculating to get a desire output current? I am asking for all conditions like 2V or 1.5V etc.
 

The datasheet saying sense voltage minimum -1 v to 2V. It may vary! for 1.5V = 1.97E, 2V = 2.6E. Advise to verify practically(trial and error method ) . Sorry for the confusion i mean Power 1W or More.
 

I have downloaded many of datasheet but no more contented information about current controlling.
Can you give me datasheet link that have all information about it?
 

Does "jam" mean braking/stopping with powered electrical method on at both sides of motor? Is it that if one side is 0.76A, and the other side is 0.76A, to jam/brake the motor, then because both are on you will get ~1.52A, as both are on?

I'm probably wrong, maybe I haven't understood the question, but it may not be possible to control (physical) laws like 1 + 1 = 2 . Maybe some-one else has a solution for that.
 

Will it not work with sensing resister change. But Data says that "Between this pin and ground is connected the sense resistor to
control the current of the load".

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I will trying to connect a variable rasistence at the place of it.

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Please tell me any other solution if possible. I am ready to change in my schematic and connect external part for current controlling.
 

I think the question is well understandable, you want to implement a current limiter at about 0.76 A. I presume, you want to raise the limit slightly above the regular load current, otherwise there's a "chance" that the loaded motor will never spin up.

You have actually connected the current sense resistor at pin 1/15, you can implement a pwm constant current circuit similar to that implemented in the L297 step motor controller used with L298.
 

What happened what is the maximum current flowing to motor, Note you should use high power resistor above 1W,

Please refer below link for more information...
https://www.bristolwatch.com/L298N/
 

Hi

I have make solution of my requirement by change the variable type sensing resister and find that It's actual value is 1.81E and going maximum 1.02A. It's working properly. It was a safety point, if accidentally anything and/or human body comes in its aria, it will not force on that.

Thanks All for your interest and valued advises.
 

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