DRV8886AT Datasheet, PDF (23/40 Pages) Texas Instruments – 2-A Stepper Motor Driver With Integrated Current Sense and AutoTune Technology

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7.3.6.4 Mode 4: AutoTune Dynamic Decay
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DRV8886AT
SLVSDO1 – JANUARY 2017
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Figure 21. AutoTune Dynamic Decay Mode
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AutoTune Dynamic Decay greatly simplifies the decay mode selection by automatically configuring the decay
mode between slow, mixed, and fast decay. In mixed decay, AutoTune dynamically adjusts the fast decay
percentage of the total mixed decay time. This feature eliminates motor tuning by automatically determining the
best decay setting that results in the lowest ripple for the motor.
The decay mode setting is optimized iteratively each PWM cycle. If the motor current overshoots the target trip
level, then the decay mode becomes more aggressive (add fast decay percentage) on the next cycle to prevent
regulation loss. If a long drive time must occur to reach the target trip level, the decay mode becomes less
aggressive (remove fast decay percentage) on the next cycle to operate with less ripple and more efficiently. On
falling steps, AutoTune Dynamic Decay automatically switches to fast decay to reach the next step quickly.
AutoTune Dynamic Decay is optimal for applications that require minimal current ripple but want to maintain a
fixed frequency in the current regulation scheme.
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