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| DRV8880_15 Datasheet, PDF (21/48 Pages) Texas Instruments – DRV8880 2-A Stepper Motor Driver With AutoTune™ | |||
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www.ti.com
7.3.5.1 Mode 1: Slow Decay for Increasing and Decreasing Current
ITRIP
DRV8880
SLVSD18A â JUNE 2015 â REVISED JULY 2015
tBLANK
tDRIVE
tOFF
tBLANK
tDRIVE
tOFF
ITRIP
tBLANK
tDRIVE
tOFF
tBLANK
tDRIVE
tOFF
Figure 16. Slow/Slow Decay Mode
tBLANK
tDRIVE
During slow decay, both of the low-side FETs of the H-bridge are turned on, allowing the current to be
recirculated.
Slow decay exhibits the least current ripple of the decay modes for a given tOFF. However on decreasing current
steps, slow decay will take a long time to settle to the new ITRIP level because the current decreases very
slowly.
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 may require a large off-time. In some cases this may cause a loss
of current regulation, and a more aggressive decay mode is recommended.
Copyright © 2015, Texas Instruments Incorporated
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