L6470 & Maximum currect limiting

[gilad2399]

Posted on February 28, 2013 at 11:20

Hi,

I'm evaluating the L6470 for a project. Going over the datasheet I noticed that the minimum value for 'maximum current limiting' is 375mA. I need to drive a very small stepper (6mm) with 12V power source. According to the manufacture, the current should be limited to 100mA. Most stepper drivers have a simple sense resistor for limiting the current, unfortunately the L6470 doesn't. I can get a 5V variation of the motor that can handle a higher current (410mA) but the driver is designed for 8V (minimum) Is there a way to solve this issue, limit the current to 100mA in some way so I could use the L6470 in my project? Thanks Gilad. #l6470-stepper-driver-current

[Enrico Poli]

Posted on March 05, 2013 at 13:37

Hi,

There is no way to obtain a lower overcurrent threshold using the L6470, but in my opinion you do not need to use a lower overcurrent threshold.The voltage mode algorithm, when properly set, keeps the phase current within the target range. The current could be higher only if a stall event occurs, and in this case you can use the sensorless stall detection to check the anomalous condition and disable the power stage (HardHiZ). Usually the motors can sustain a current higher than the maximum rating for a short period.You can also use the 5V variation of the motor if you want. In fact

the voltage rating of the stepper motor is not the maximum voltage you can apply to the phases

, but just the voltage which applied to the motor generates the rating current. Using a PWM technique you can drive the motor using an higher supply voltage, in this case the results are even better because you can force higher phase currents (i.e. torque) when the motor speed increase.Kind RegardsEnrico