DRV8812: Decay mode question/confirmation

Hi Kitajima-san,

1: Using Aout/Bout independently, can we change the decay mode during controlling the motor?

For instance, while Aout is in operation, change the mode to fast, and while Bout is in operation, change the mode to slow.

Yes, you can change the decay mode. The decay mode set applies to both the AOUT and BOUT. So it is not possible to run AOUT with fast and BOUT with slow at the same time.

2: Based on the datasheet, Mixed decay is open, Logic High is above 2.0V, and Logic Low is below 0.8V.

The customer is thinking if the logic voltage is between 0.8 and 2.0V, it should enter mixed decay. Is this correct?

Mixed decay is between 0.8 and 2.0V, and should be ~1.4V typical.

#3: Relating to #1, when does the decay mode change after inputting logic to DECAY Pin?

Is there any time-based reference based on the clock?

The decay mode changes at the beginning of the next PWM cycle.

Please consider the DRV8881E as a possible alternative. The DRV8881E has two DECAY pins, ADECAY and BDECAY.

Hi Kitajima-san,

When set to open, the DECAY pin should be ~1.25V.

If inputting an external voltage, it is estimated that a voltage between 1.0V and 1.7V should set the decay mode as mixed.