Part Number:DRV8308
Hello there,
I have a DRV8308 EVM which has the rev. a chip and its document stated the behavior when switching the direction while motor is moving:
"If the commanded direction is changed while the motor is moving, the device either brakes or allows the motor to
coast, depending on the state of the BRKMODE bit, until the motor stops. The stopped condition is determined
by measuring the period of the HALL_U signal; when the period exceeds 160 ms, typical operation resumes and
the motor starts spinning in the commanded direction. This prevents excessive current flow in the output stage if
the motor is reversed while running at speed."
The rev b version has only "If the commanded direction is changed while the motor is still spinning, this may cause excessive current flow in
the output stage."
in EVM board, my motor can rotate properly when I change direction by either giving a pwm duty cylce of 20% and flip the DIR from the GUI provided by TI or stopping motor by set pwm duty cycle to 0, then 20% and then click DIR.
Now with my own development board, which has rev b. chip. Motor might stuck which switching direction using the either one of the approach I chosen above. if I helps the motor to move a little bit, then motor would start to rotate. I don't know what is the problem and am wondering what is the behavior when DIR signal is toggled high to low or low to high: does DRV8308 simply reverse the commutation sequence based on the directional signal directly no matter if motor is rotated or not. One more behavior is that when motor stuck, the LOCK signal is still set.
thanks,
Hong