SLOS825E December 2012 – April 2018 DRV2605
This bit sets the reference voltage for full-scale output during closed-loop operation. The auto-calibration routine uses this register as an input, therefore this register must be written with the rated voltage value of the motor before calibration is performed. This register is ignored for open-loop operation because the overdrive voltage sets the reference for that case. Any modification of this register value should be followed by calibration to set A_CAL_BEMF appropriately.
See the Rated Voltage Programming section for calculating the correct register value.