SLVU681 Datasheet, PDF (7/21 Pages) Texas Instruments – DRV8818EVM Evaluation Module

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3.3.3 Current Control and Decay Modes
This set of boxes controls the reference current and the current decay modes once this current threshold
is reached.
• Decay Control: The slider allows you to control the voltage on the DECAY pin. This controls which
mode the device is in when the current is decreasing through the load on the falling edge of the
sinusoidal current. In FULL Step mode, this control does not apply. The table shows the modes as it
corresponds to the voltage applied on the DECAY pin. For example, a voltage less than 0.7 V fixes the
device in a Fast decay mode. A voltage greater than 2 V puts the device in a Slow decay more. A
voltage between 0.7 V and 2 V selects a mixed decay with a ratio of fast decay followed by slow decay
depending on the voltage set between 0.7 V and 2 V. This is easier to see on an oscilloscope capture.
• Current Control: This slider sets the voltage on VREF. The current displays on the screen based on
the following calculation:
Iref = Vref / 8 × Rsense
SLVU681 – February 2012
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