AMIS-30622 Datasheet, PDF (30/42 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30622
command to program and zap separately one OTP memory byte. A GetOTPparam command issued after each
SetOTPparam command allows verifying the correct byte zapping.
Note
Zapped bits will really be “active” after a GetOTPparam or a ResetToDefault command or after a power-up.
9.2.3. Motordriver
9.2.3.1. Current waveforms in the coils
The figure below illustrates the current fed to the motor coils by the motordriver in half-step mode.
I_coil
Coil X
Coil Y
I_run
I
run
2
t
Whereas the figure below shows the current fed to one coil in 1/16^th microstepping (1 electrical period).
I_coil
t
9.2.3.2. PWM regulation
In order to force a given current (determined by Irun or Ihold and the current position of the rotor) through the
motor coil while ensuring high energy transfer efficiency, a regulation based on PWM principle is used. The
regulation loop performs a comparison of the sensed output current to an internal reference, and features a
digital regulation generating the PWM signal that drives the output switches. The zoom over one micro-step in
the figure above shows how the PWM circuit performs this regulation.
9.2.3.3. Motor starting phase
At motion start, the currents in the coils are directly switched from Ihold to Irun with a new sine/cos ratio
corresponding to the first half (or micro) step of the motion.
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