some questions about irun of tmc223

[liaoshy]

when we apply for tmc223 in our project，have some questions about irun set：
1.we set irun=0x0d（566mA），but we test the coil perk current always about 600ma。 why？
2. when we change moter steps quickly， the coil current cann't be adjusted to perk cmaxurrent （maximum value）。but change moter steps slowly，the coil current can be。

[Dr.LarsLarsson (TRINAMIC)]

1) A current of 600mA is approx. 5% larger than a current of 566mA - this is due to internal sense resistors tolerances

2) When the steppe moves fast, the target current cannot fully be reached due to the Back EMF at finite supply voltage; the speed where this effect becomes visibly is where the amplitude of the Back EMF touches the supply voltage