tmc223: question about open circuit detect

[liaoshy]

when we apply tmc 223 ,we find some questions in open circuit detect.
1.we find for some types motor,tmc 223 can detect open circuit in 4-6 s time,but maybe for another type motor tmc223 find open detect oen circuit in 40-60s,the time is very long.
what factors affect the effect ?
2. we find when step moter keep moving, tmc223 cann't detect open circuit for long time,why?

[Dr.LarsLarsson (TRINAMIC)]

If the motor runs fast, the open load detection might become active if the target current is not reached due to back EMF of the motor and the given motor supply voltage. Depending on the motor, the actual speed needs to be taken into account.