Author Topic: Blown up L298P DC Motor Driver - what is the reason ?  (Read 848 times)

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Offline ciseliTopic starter

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Blown up L298P DC Motor Driver - what is the reason ?
« on: March 05, 2019, 06:32:27 pm »
Hello,

I am driving a brushed DC motor, 24V 0.5A in an actuator with a L298P.

For the second time I have caused the magic smoke to escape from the L298P.

The first time I am pretty sure the cause was that I reversed the direction bit without taking enable low, probably causing a short between the 2 power transistors of the bridge.  I just had a small resistive load during that test.

The second time, I made sure to disallow direction changing while enable is on, and added 20 millisecond delay after lowering enable before flipping the direction bit... and yet I obtained a nice big spark and fumes, and the results are shown on the attached picture.  L298P blown up with visible hole in the casing...



My current impression is that probably the motor was still spinning due to inertia while I did the direction flipping after 20 milliseconds and putting enable on after 10 more milliseconds.

Any other ideas of probable/possible causes ?

Thanks and kind regards,
Christian
 

Offline RES

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Offline fcb

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Re: Blown up L298P DC Motor Driver - what is the reason ?
« Reply #2 on: March 05, 2019, 09:33:25 pm »
The L298 is not very robust and dies very easily.  Not super helpful I know.

On a practical note, make sure you have FAST back emf diodes protecting the outputs - 1N4001 probably not good enough.  Also, are you using a current sensing resistor? Make sure it's low inductance and the 'appropriate' size, it can help 'cushion' the start-up.
https://electron.plus Power Analysers, VI Signature Testers, Voltage References, Picoammeters, Curve Tracers.
 
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