I have “dual MC33926 motor driver shield for Arduino” and I am planning to use it for torque control design. But I am confused about feedback voltage. It is not giving the voltage which is described in the formula (datasheet desek mi). Normally it supposed to give 525 mV/A. But I checked by multimeter from FB pins and I measured as 425 mV/A.
I’m adding my algorithm, codes and screenshoots of my demo design for feedback test. 7.6 ohm resistor connected to driver shield as a load and it is driven with the current of 1 A which is shown in the attached image. Also, measured voltage is 425 mV and current is 792 mA at serial port through Arduino.
So my question is, what might be the problem about my “MC33926 driver shield”. I hope I clearly stated the problem. I really appreciate if you can help me in order to handle this confusion out. If you need further information I hopefully can support it.
The current sense feedback in the MC33926 is not a precision measurement, so 525 mV/A represents an approximate typical value, and individual drivers might have different characteristics. The numbers in the datasheet indicate an accuracy of ±20%, and it appears your particular unit is near the edge of that range, but still not necessarily abnormal. If your application needs to be more precise and accurate, you might consider characterizing the feedback across a range of currents to figure out the equation for each of your MC33926 drivers.