L6235n Heats Up While Driving BLDC motor

[Learning_goal]

I am using L6235n circuit given in this application note to drive a BLDC motor. The nominal current rating (max continuous current) of the motor is 2.32A.
https://www.st.com/st-web-ui/static...ical/document/application_note/CD00004396.pdf


I am using a DAC IC to provide the DAC input required at Vref, without using the feedback at Vref. But my motor driver gets heated up after using for sometime.
Can anyone tell me what might be the problem or how to use this driver IC?
Thanks

 

[FvM]

What do you mean with "feedback at Vref"? There's no feedback at Vref involved in the application note circuit. The value of the current sense resistor and Vref are setting the motor current, both should be chosen meaningful. Also the RCoff dimensioning matters because it sets the switching frequency.

 

[Learning_goal]

Sir,
By feedback I meant the tacho feedback using Op-Amp as shown in the circuit.
My circuit doesn't have op-amp circuitary, rather directly an analog voltage is supplied to the Vref pin.
The motor driver is heating up very much.
I tested the circuit removing Cin as well, still the IC heats up rapidly. The typical current consumed by the IC is 0.7 A and it start increasing. After reaching 0.9 A, the DIAG voltage starts to fluctuate between 5V and 0V.
Please help.
If something is wrong with the implementation of the circuit, please do tell.
Thanks.

 

[FvM]

The DIAG output signals overcurrent or overheating.

I can just guess that something's wrong with the current sense and current limiting circuit. It's necessary to check the output waveforms with an oscilloscope.