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| DRV8880_15 Datasheet, PDF (23/48 Pages) Texas Instruments – DRV8880 2-A Stepper Motor Driver With AutoTune™ | |||
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www.ti.com
7.3.5.3 Mode 3: Mixed Decay for Increasing and Decreasing Current
ITRIP
DRV8880
SLVSD18A â JUNE 2015 â REVISED JULY 2015
tDRIVE
tOFF
tBLANK
tDRIVE
tOFF
tBLANK
tDRIVE
ITRIP
tBLANK
tDRIVE
tFAST
tOFF
tBLANK
tDRIVE
tFAST
tOFF
Figure 18. Mixed/Mixed Decay Mode
Mixed decay begins as fast decay for a time, followed by slow decay for the remainder of tOFF. In this mode,
mixed decay occurs for both increasing and decreasing current steps.
This mode exhibits ripple larger than slow decay, but smaller than fast decay. On decreasing current steps,
mixed decay will settle to the new ITRIP level faster than slow decay.
In cases where current is held for a long time (no input in the STEP pin) or at very low stepping speeds, slow
decay may not properly regulate current because no back-EMF is present across the motor windings. In this
state, motor current can rise very quickly, and requires an excessively large off-time. Increasing/decreasing
mixed decay mode allows the current level to stay in regulation when no back-EMF is present across the motor
windings.
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV8880
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