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[PIC] L298 and Stepper Motor Getting HOT..

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Junior Member level 3
Jun 23, 2013
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Hello everyone.!
I'm making stepper motor control project with L297 and two L298 for stepper motor rated 2Amp capacity.These are parameter for L297

Reset pin 20 = 1 (+5V)
Pin 16 Osc = recommended circuit used as per datasheet
Pin 15 Vref = 0.36 V
Pin 11 Control = 1
Pin 10 Enable = 1
Current sensing resistor = 0.5 ohm ( 1 Ohm resistance 1 watt parallel )

Power Supply = 12 V , 2.1 Ampere
Motor Running = 1 Ampere ( By adjusting vref and sense resistor )

Now the motor is running very well forward and reverse.But I need Locking state in which rotor remains lock according to my application.

Now the problem is that after few minutes the motor getting very hot and L298 both near about to burn. I don,t know exactly what to do now..

Thanks in advance..

Hi. Don't stepper motors stay locked in position when no signal is applied? Maybe not, that's what I'd understood. Would disabling the oscillator during the locking state help?
If you have one, maybe posting a schematic of your circuit might be helpful so other members can help trouble-shoot with you.
I vaguely recollect that the L298 is meant for quite small motors, I've only used one with 5V and approx. 50mA to 150mA stepper and DC motors. When I used to read about the L298 the term "gets hot quickly" appeared very often.

L298 is old bipolar technology with limited efficiency. In so far it surely won't stay cool. There may be a problem of irregular (too fast) switching, you should check the waveforms with an oscilloscope.

In most SM applications that require hold current, the current can be reduced. This is possible by controlling L297b Vref input.
@fvM : first of all thank you sir for your time and reply. Sir I'm making an application in which motor turns either forward or backward as the motor finished its task it remain stops and the shaft has been locked. It holds the one position by blocking the rotor shaft.

For that purpose I turn the clock into 0 signal from controller.

Sir ,what is holding current ..?? How i can set to the Vref pin. I already set the 0.37V for vref on the holding stage of SM. Is this value high.?
what are the Vref values for running and state of motor.?

It would be a great help

Thanks in advance.. :)

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@FvM: Sir can i applied ground signal to the L297 Vref Pin for lower down the current and heat of stepper motor.?

You should try if you're drive has suffciient holding torque with less current. Current is proportional to Vref.

what about stepper motor heating problem , sir..?

Essentially the same answer, try reduced holding current.

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