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DRV8424: DVDD value at VM=4.8V?

Stefan Lintner
Expert 5185 points
Part Number: DRV8424

Hi Team,

my customer is considering DRV8424 to drive a DC motor. could you please help to answer their questions regarding DVDD?

We power the DRV with VM = 4.8V. This is acceptable because the datasheet gives an operating range from 4.5 to 33V.

The datasheet specifies the DVDD range from 4.5V to 5.5 for VM > 6V. With VM = 4.8V, what will be the voltage on DVDD?

 

For quad-levels logic input, one of the four logical state is “tied to DVDD” and the voltage range is given between 2.7 and 5.5V. What shall we do? Use a “unknown” DVDD or use an external 3V3 instead?

It is also recommended to use DVDD to create VREFx through divider bridges. It seems clear that we should not do that when VM < 6V since DVDD is undefined leading to unprecise VREF. Is it right?

BR,
Stefan

  • 0
    TI__Guru 56650 points

    Stefan,

    The DVDD output should come from an internal low drop LDO. It will be lower than 4.8V, I am confirming the value with system and design team.

    Since DVDD active voltage is always higher 2.7V even VM=4.5V. To get high for quad-levels logic input, "“tied to DVDD” or use an external 3.3V both are OK.

    "It is also recommended to use DVDD to create VREFx through divider bridges. It seems clear that we should not do that when VM < 6V since DVDD is undefined leading to unprecise VREF." Yes

  • 0 in reply to Wang5577
    TI__Expert 5185 points

    Thank you for your fast reply Wang!

    So this confirms what I was thinking. I will use an external 3V3 for both quad-level input and VREF. I leave DVDD connected to a decoupling capacitor but nothing else.

     BR,

    Stefan

  • 0 in reply to Stefan Lintner
    TI__Guru 56650 points

    Stefan,

    The system engineer confirmed: At 4.5V supply, the DVDD typically will be 4.35V and 4.2V minimum.