EVAL6470H Datasheet, PDF (35/70 Pages) STMicroelectronics – dSPIN fully integrated microstepping motor driver with motion engine and SPI

L6470
7.2
Phase current control
Sensorless stall detection
Depending on motor speed and load angle characteristics, the L6470 offers a motor stall
condition detection using a programmable current comparator.
When a stall event occurs, the respective flag (STEP_LOSS_A or STEP_LOSS_B) is forced
low until a GetStaus command or a system reset occurs (see Section 9.2.20).
7.3
Low speed optimization
When the motor is driven at a very low speed using a small driving voltage, the resulting
phase current can be distorted. As a consequence, the motor position is different from the
ideal one (see Figure 15).
The L6470 implements a low speed optimization in order to remove this effect.
Figure 15. Current distortion and compensation
7ITHOUTLOWSPEEDOPTIMIZAZION
)_PHASE
7ITHLOWSPEEDOPTIMIZAZION
)_PHASE
#URRENTDISTORTIONISHEAVILY
REDUCED
!-6
The optimization can be enabled setting high the LSPD_OPT bit in the MIN_SPEED register
(see Section 9.1.8) and is active in a speed range from zero to MIN_SPEED. When low
speed optimization is enabled, speed profile minimum speed is forced to zero.
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