Tool/software:
I am trying to build a motor control board for a stepper motor. I wish to incorporate a power up routine feature, where in the during the power up, the control should be able to detect a grounded motor coil. Can I use the Overcurrent Protection (OCP) feature in DRV8825 driver to build this feature? Did anyone/TI implement this kind of feature in their projects?
Hi Subhashitha,
Thanks for your post.
When powered up and its outputs enabled with nENBL input with proper A,BVREF inputs, and if one of the outputs shorted to GND, the DRV8825 will detect an overcurrent because the output current would exceed IOCP for longer than its deglitch time and disable the bridge to protect the device.
That said, it is possible in rare occasions, that the coil was shorted to GND at its center region offering an impedance to GND. If the coil current then stays < IOCP an overcurrent event will never happen. This is how OCP works in this device and most integrated drivers in our portfolio. So it is possible for a coil to have a short and unable to trigger an OCP event.
I am trying to build a motor control board for a stepper motor. I wish to incorporate a power up routine feature, where in the during the power up, the control should be able to detect a grounded motor coil. Can I use the Overcurrent Protection (OCP) feature in DRV8825 driver to build this feature?
The OCP feature in the device will work continuously, not at just power up. nFAULT can indicate a fault for TSD and UVLO situations as well, however for these two faults the recovery will be automatic when the fault condition is removed whereas with OCP, the device will not recover until this fault is reset. Like I mentioned, there could be a situation where there is a short but not enough to have the current exceed IOCP - in this situation the short cannot be detected as OCP.
Regards, Murugavel
