DRV8426PWPR datasheet(19/49 Pages) TI1

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DRV8426

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SLOSE55 – MAY 2020

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7.3.6.1 Slow Decay for Increasing and Decreasing Current

Figure 10. Slow/Slow Decay Mode

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. If the current at the end of the off time is above the ITRIP level, slow decay will be extended for another

off time duration and so on, till the current at the end of the off time is below ITRIP level.

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.

DRV8426PWPR Datasheet(PDF) 19 Page - Texas Instruments