DRV8306: It is diffcult to start the motor with DRV8306

Hello TI official:

          I have a question, Our team had difficulty starting the motor when using DRV8306. When the motor is unloaded, it can be started normally most of time.

However, when the motor is loaded, even if the loaded is small, there is a problem of starting difficulty. At this time, if we give the motor a torque, then the motor 

can be started.

         So I want to ask how to solve this problem.

                                                                                                                                                                       Looking forward to your reply

                                                            DRV8306.pdf                                                                                                           Thank you                                       

Cherry Zhou：

Hi,

Please allow some time for our experts to look into this issue.

Thanks

,

Cherry Zhou：

Hi,

Could I be provided with two captures, one with SHx, GHx, GLx, and VDRAIN and the other with the input PWM, SHX, and ISEN, when the motor is commanded to begin spinning? I want to check if Vlimit is being exceeded which would be limiting the current available to the motor.

Thanks

,

happy：

Thank you for your advice, but it is difficult for me to measure these signals, so I redrew the PCB and prepared to collect these signals. 

,

happy：

I will test the above signal after the new PCB is made.

There's one more question I want to ask. 

It is on your official evalution board, The HPx is connected to the DVDD by pull-up resistor, and the HNx is connected to the DVDD/2 by divider resistor.(single-ended Halls signals)

For me, I connected the HPx to the DVDD by pull-up resistor too, but I connected the HNx directly to GND.

Is there any problem with this connection ?

Is it possible that because of this connection caused the  motor can not start with load?

,

Cherry Zhou：

Hi,

Due to a holiday, Our expert is on vacation kindly expect a 1~2 day delay in responses.

,

Cherry Zhou：

Hi,

Connecting the HNx pins to GND should not lead to an issue with being able to drive a motor, especially if the motor can spin without load with no issues.

Usually being able to spin without load and then seeing issues with startup with a load, but spinning with the load is operating fine, indicates that there is not enough current available to the motor to overcome the required starting torque.

Thanks