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DRV8886: Minimum Ifs under controlling RREF with external DAC

Part Number: DRV8886

Hi Team,

My customer wants to minimize Ifs by controlling external DAC like indicated in "Controlling RREF With an MCU DAC" capture of datasheet.
According to the datasheet, VRREF is estimated around 1.18 ~ 1.28V, so To set the Ifs to a minimum value, the DAC output must be set to 1.28V. But DAC output voltage > VRREF condition is not recommended in the datasheet also.

Then, they have following two questions.

1. what are the specific risks of (DAC output voltage > VRREF) condition?

2. Does the DAC output need to be up to 1.18 V?

Regards,

Takashi Onawa

  • Hi Onawa-san,

    There are no risks with DAC output voltage > VRREF.

    What is the desired minimum current Ifs?  When the DAC is set to 1.18 to 1.28V, the current is effectively zero.

    Zero current can also be achieved by setting the ENABLE to low.