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Speed Control problem with L6235 DIP

Question asked by Vijay K Yadav on Oct 25, 2016
Hi All,
I want to make a BLDC motor driver board using L6235N DIP.
I wired all the components on the breadboard as per schematic diagram and component list is given in ST Application Note AN1625 page no. 35-37.
I am using PWM from MCU to control the speed of the BLDC motor(Max Speed 3000RPM). Now motor is running and break, Direction, Tacho all these features are working fine but I have a little problem to control the speed .

generally, when I set the PWM duty Cycle 0% Motor should be stop but still motor is running arround 350RPM. PWM output is connected with Vref pin no. 13 of L6235N. I am unable to control the speed less than 350RPM but more than 350RPM Speed control is working fine.  When I connect the PIN no. 13 (Vref) to 0V(Signal Ground) nothing changed motor still running at 350RPM but it should be stopped. I am using all the components as per given Application note AN1625.
I am unable to find out the problem. Any help would be appreciated.

Thanks in advance,


Vijay K Yadav