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DRV8841: Usage of the decay pin

Shubham Thorat
Prodigy 30 points
Part Number: DRV8841

Hello,

As per the datasheet the decay pin controls the decaying mode of the motor coil. However the decaying path can also be provided by making XIN1 "low" and XIN2 "high" for fast decaying ;and making both XIN1 and XIN2 "low" for slow decaying. Provided that for increasing current , XIN1 is made "high" and XIN2 is  made "low". then why is 'DECAY' pin provided ?

  • 0
    TI__Genius 14487 points
    Shubham,

    You are correct that someone could program a microcontroller to perform fast and slow decay with the right combination of xINx signals. However, using the DECAY pin helps to offload this process from the microcontroller, and the microcontroller would also need to sense the current through the windings.

    When you use the DECAY pin, the DRV8841 performs the current regulation internally. It will maintain the desired current level in the windings using the mode you choose with the DECAY pin. The DRV8841 regulates the current according to the voltage set on the VREF pins. To perform microstepping, you supply a voltage from a DAC to the VREF pins depending on the current level you require.